Showing papers on "p–n junction published in 2017"
TL;DR: In this article, the authors demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p-n junctions in a MoSe2-WSe2 heterobilayer.
Abstract: Semiconductor heterostructures are backbones for solid-state-based optoelectronic devices. Recent advances in assembly techniques for van der Waals heterostructures have enabled the band engineering of semiconductor heterojunctions for atomically thin optoelectronic devices. In two-dimensional heterostructures with type II band alignment, interlayer excitons, where Coulomb bound electrons and holes are confined to opposite layers, have shown promising properties for novel excitonic devices, including a large binding energy, micron-scale in-plane drift-diffusion, and a long population and valley polarization lifetime. Here, we demonstrate interlayer exciton optoelectronics based on electrostatically defined lateral p–n junctions in a MoSe2–WSe2 heterobilayer. Applying a forward bias enables the first observation of electroluminescence from interlayer excitons. At zero bias, the p–n junction functions as a highly sensitive photodetector, where the wavelength-dependent photocurrent measurement allows the dir...
256 citations
TL;DR: In this article, a self-powered ultraviolet photodetector was constructed with GaN/Ga2O3 p-n junction by depositing n-type Ga 2O3 thin film on Al2O 3 single crystals substrate covered by p-type GAN thin film, which exhibits a typical rectification behavior in dark and excellent photovoltaic characteristics under 365 nm and 254 nm light illumination.
Abstract: A self-powered ultraviolet photodetector was constructed with GaN/Ga2O3 p–n junction by depositing n-type Ga2O3 thin film on Al2O3 single crystals substrate covered by p-type GaN thin film. The fabricated device exhibits a typical rectification behavior in dark and excellent photovoltaic characteristics under 365 nm and 254 nm light illumination. The device shows an extremely high responsivity of 54.43 mA W−1, a fast decay time of 0.08 s, a high Ilight/Idark ratio of 152 and a high detectivity of 1.23 × 1011 cm Hz1/2 W−1 under 365 nm light with a light intensity of 1.7 mW cm−2 under zero bias. Such excellent performances under zero bias are attributed to the rapid separation of photogenerated electron–hole pairs driven by built-in electric field in the interface depletion region of GaN/Ga2O3 p–n junction. The results strongly suggest that the GaN/Ga2O3 p–n junction based photodetectors are suitable for applications in secure ultraviolet communication and space detection which require high responsivity and self-sufficient functionality.
209 citations
TL;DR: This work helps to understand the fundamentals of tunneling in 2D semiconductor heterostructures and shows great potential in future applications in integrated low-power circuits.
Abstract: Diverse diode characteristics were observed in two-dimensional (2D) black phosphorus (BP) and molybdenum disulfide (MoS2) heterojunctions. The characteristics of a backward rectifying diode, a Zener diode, and a forward rectifying diode were obtained from the heterojunction through thickness modulation of the BP flake or back gate modulation. Moreover, a tunnel diode with a precursor to negative differential resistance can be realized by applying dual gating with a solid polymer electrolyte layer as a top gate dielectric material. Interestingly, a steep subthreshold swing of 55 mV/dec was achieved in a top-gated 2D BP–MoS2 junction. Our simple device architecture and chemical doping-free processing guaranteed the device quality. This work helps us understand the fundamentals of tunneling in 2D semiconductor heterostructures and shows great potential in future applications in integrated low-power circuits.
146 citations
TL;DR: In this article, the formation of Cu 2 FeSnS 4 (CFTS) thin-films through successive ionic layer adsorption and reaction (SILAR) method is presented.
87 citations
TL;DR: This work shows how to manipulate the charge carriers by using a circular p-n junction whose size can be continuously tuned from the nanometre to the micrometre scale, which traps the Dirac electrons in quantum-confined states, which are the graphene equivalent of the atomic collapse states predicted to occur at supercritically charged nuclei.
Abstract: A transition from optical transport to quantum confinement, observed in a size-tunable circular graphene p–n junction could enable switching and guiding of Dirac electrons. The photon-like propagation of the Dirac electrons in graphene, together with its record-high electronic mobility1,2,3, can lead to applications based on ultrafast electronic response and low dissipation4,5,6. However, the chiral nature of the charge carriers that is responsible for the high mobility also makes it difficult to control their motion and prevents electronic switching. Here, we show how to manipulate the charge carriers by using a circular p–n junction whose size can be continuously tuned from the nanometre to the micrometre scale7,8. The junction size is controlled with a dual-gate device consisting of a planar back gate and a point-like top gate made by decorating a scanning tunnelling microscope tip with a gold nanowire. The nanometre-scale junction is defined by a deep potential well created by the tip-induced charge. It traps the Dirac electrons in quantum-confined states, which are the graphene equivalent of the atomic collapse states (ACSs) predicted to occur at supercritically charged nuclei9,10,11,12,13. As the junction size increases, the transition to the optical regime is signalled by the emergence of whispering-gallery modes14,15,16, similar to those observed at the perimeter of acoustic or optical resonators, and by the appearance of a Fabry–Perot interference pattern17,18,19,20 for junctions close to a boundary.
84 citations
TL;DR: In this paper, the authors have fabricated a novel CuO/PbTiO3 p-n junction by a simple impregnation method and examined its photocatalytic activity towards the degradation of malachite green.
Abstract: An innovative tactic is to architecture novel p–n junctions for the efficient separation of charge carriers at heterojunction interfaces and enhance the photocatalytic activity under visible light irradiation. In view of this, we have fabricated a novel CuO/PbTiO3 p–n junction by a simple impregnation method and examined its photocatalytic activity towards the degradation of malachite green. First and foremost, the photoelectrochemical measurements confirmed the n-type and p-type semiconducting properties of PbTiO3 and CuO, respectively. The measured asymmetric photocurrent in opposite directions and the rectifying behaviour of all the prepared heterojunctions confirmed the formation of a p–n junction between the CuO and PbTiO3. The TEM results reveal that the p-type CuO nanoparticles were successfully assembled on the surface of the polyhedron-shaped n-type PbTiO3 and a strong p–n junction interface was formed between them. A regular study is represented for the detailed characterization of the phases, surface chemical composition, surface morphology, and optical properties of the prepared heterojunctions. All the CuO/PbTiO3 p–n junctions exhibited superior photocatalytic activity for the degradation of malachite green (MG) under visible light irradiation compared to neat PbTiO3 and CuO. The superior photocatalytic activity of the p–n junction samples was due to the efficient separation of charge carriers at the junction interface. The efficient separation of charge carriers at the p–n junction interface was confirmed by EIS, steady state, and time-resolved PL analysis. The 33% CuO/PbTiO3 p–n junction reveals a higher activity around 91% degradation of malachite green under visible light irradiation in comparison to the other p–n junctions. The kinetic analysis of the prepared photocatalysts for malachite green (MG) degradation showed that the process followed a pseudo-first-order kinetics model.
73 citations
TL;DR: A hybrid system based on topological insulator Bi2Se3 nanoflake and Si nanowire as the newest efficient candidate for advanced optoelectronic materials is established.
Abstract: Chemically derived topological insulator Bi2Se3 nanoflake/Si nanowire (SiNWs) heterojunctions were fabricated employing all eco-friendly cost-effective chemical route for the first time. X-ray diffraction studies confirmed proper phase formation of Bi2Se3 nanoflakes. The morphological features of the individual components and time-evolved hybrid structures were studied using field emission scanning electron microscope. High resolution transmission electron microscopic studies were performed to investigate the actual nature of junction whereas elemental distributions at junction, along with overall stoichiometry of the samples were analyzed using energy dispersive X-ray studies. Temperature dependent current–voltage characteristics and variation of barrier height and ideality factor was studied between 50 and 300 K. An increase in barrier height and decrease in the ideality factor were observed with increasing temperature for the sample. The rectification ratio (I+/I–) for SiNWs substrate over pristine Si ...
63 citations
TL;DR: In this paper, a theoretical study on the equilibrium state of a PN junction, which is created by two piezoelectric semiconductor half spaces doped oppositely, based on the equations of linear PNE and the conservation of charge for holes and electrons, is presented.
Abstract: We present a theoretical study on the equilibrium state of a PN junction, which is created by two piezoelectric semiconductor half spaces doped oppositely, based on the equations of linear piezoelectricity and the conservation of charge for holes and electrons. The nonlinearity associated with the drift currents of electrons and holes, which appears as products of the unknown carrier concentrations and the unknown electric field, is linearized for small carrier concentration perturbations. An analytical solution is rigorously derived, which is able to show the shaping of the PN junction near the interface. The electromechanical fields and concentrations of electrons and holes near the interface of the PN junction, and the forward-bias current-voltage characteristics of the PN junction under different applied stresses, are calculated and discussed. The effects of a few physical parameters on the properties of the PN junction are investigated as well.
61 citations
TL;DR: The results show that a dense robust silicon thinFilm with embedded junction formation can be produced directly from inexpensive silicates/silicon oxide precursors by a two-step electrodeposition process, indicating promise for application in low-cost silicon thin film solar cells.
Abstract: Herein we report the demonstration of electrochemical deposition of silicon p–n junctions all in molten salt. The results show that a dense robust silicon thin film with embedded junction formation can be produced directly from inexpensive silicates/silicon oxide precursors by a two-step electrodeposition process. The fabricated silicon p–n junction exhibits clear diode rectification behavior and photovoltaic effects, indicating promise for application in low-cost silicon thin film solar cells.
54 citations
TL;DR: It has been confirmed that the CF is consisting of the oxygen vacancy by in-situ TEM characterization, and the formation of CF does not degrade the diode performance, which allows the coexistence of RS and rectifying behaviors, revealing the 1D1R switching model.
Abstract: One diode-one resistor (1D1R) memory is an effective architecture to suppress the crosstalk interference, realizing the crossbar network integration of resistive random access memory (RRAM). Herein, we designed a p+-Si/n-ZnO heterostructure with 1D1R function. Compared with the conventional multilayer 1D1R devices, the structure and fabrication technique can be largely simplified. The real-time imaging of formation/rupture process of conductive filament (CF) process demonstrated the RS mechanism by in-situ transmission electron microscopy (TEM). Meanwhile, we observed that the formed CF is only confined to the outside of depletion region of Si/ZnO pn junction, and the formation of CF does not degrade the diode performance, which allows the coexistence of RS and rectifying behaviors, revealing the 1D1R switching model. Furthermore, it has been confirmed that the CF is consisting of the oxygen vacancy by in-situ TEM characterization.
34 citations
TL;DR: In this paper, an organic vertical p-n junction (p-type pentacene/n-type N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8)) on top of a graphene electrode constituting a novel gate-tunable photodiode device structure is fabricated.
Abstract: Monolayer graphene is used as an electrode to develop novel electronic device architectures that exploit the unique, atomically thin structure of the material with a low density of states at its charge neutrality point. For example, a single semiconductor layer stacked onto graphene can provide a semiconductor–electrode junction with a tunable injection barrier, which is the basis for a primitive transistor architecture known as the Schottky barrier field-effect transistor. This work demonstrates the next level of complexity in a vertical graphene–semiconductor architecture. Specifically, an organic vertical p-n junction (p-type pentacene/n-type N,N′-dioctyl-3,4,9,10-perylenedicarboximide (PTCDI-C8)) on top of a graphene electrode constituting a novel gate-tunable photodiode device structure is fabricated. The model device confirms that controlling the Schottky barrier height at the pentacene–graphene junction can (i) suppress the dark current density and (ii) enhance the photocurrent of the device, both of which are critical to improve the performance of a photodiode.
TL;DR: The fabrication of hybrid PN junction diode and complementary (CMOS) inverters, where 2D p-type MoTe2 and n-type thin film InGaZnO (IGZO) are coupled for each device process, exhibits voltage gains as high as ∼40 at 5 V, low power consumption less than around a few nW at 1 V, and ∼200 μs switching dynamics.
Abstract: We report the fabrication of hybrid PN junction diode and complementary (CMOS) inverters, where 2D p-type MoTe2 and n-type thin film InGaZnO (IGZO) are coupled for each device process. IGZO thin film was initially patterned by conventional photolithography either for n-type material in a PN diode or for n-channel of top-gate field-effect transistors (FET) in CMOS inverter. The hybrid PN junction diode shows a good ideality factor of 1.57 and quite a high ON/OFF rectification ratio of ∼3 × 104. Under photons, our hybrid PN diode appeared somewhat stable only responding to high-energy photons of blue and ultraviolet. Our 2D nanosheet–oxide film hybrid CMOS inverter exhibits voltage gains as high as ∼40 at 5 V, low power consumption less than around a few nW at 1 V, and ∼200 μs switching dynamics.
TL;DR: In this article, a bifunctional CdS@MoS 2 core-shell nanorod arrays with photo-and electrocatalytic activity for hydrogen evolution reaction (HER) were presented.
TL;DR: It is found that the built-in potential becomes negative under a forward bias voltage range where field-induced TMD p-n junctions have been operated as light-emitting diodes and well reproduced the circularly polarized electroluminescence from the WSe2 p- n junction.
Abstract: Electric field-induced p–n junctions are often used to realize peculiar functionalities in various materials. This method can be applied not only to conventional semiconductors but also to carbon nanotubes, graphene, and organic semiconductors to which the conventional chemical doping method is difficult to apply. Transition-metal dichalcogenides (TMDs) are one of such materials where the field-induced p–n junctions play crucial roles in realizing solar cell and light-emitting diode operations as well as circularly polarized electroluminescence. Although the field-induced p–n junction is a well-established technique, many of its physical properties are left to be understood because their doping mechanism is distinct from that of conventional p–n junctions. Here we report a direct electrical measurement of the potential variation along the field-induced p–n junction using multiple pairs of voltage probes. We detected the position of the junction, estimated the built-in potential, and monitored the effect o...
TL;DR: In this paper, a method of chemically p-doping films of thiol-capped PbS QDs was presented, which showed an improvement in the power conversion efficiency from 7.1% to 7.6%.
Abstract: Lead sulfide quantum dot (PbS QD) solar cell efficiencies have improved rapidly over the past years due in large part to intelligent band alignment considerations. A pn-junction can be formed by connecting PbS layers with contrasting ligands. However, the resulting doping concentrations are typically low and cannot be effectively controlled. Here, we present a method of chemically p-doping films of thiol capped PbS QDs. P-n junction solar cells with increased doping in the p-type layer show improved short circuit current and fill factor, leading to an improvement in the power conversion efficiency from 7.1% to 7.6%. By examining Schottky diodes, field effect transistors, and the absorption spectra of treated and untreated PbS QDs, we show that the improved efficiency is due to the increased doping concentration in the thiol capped QD layer and to denser packing of the PbS QD film.
TL;DR: In this paper, a p-n junction device was fabricated by depositing an n-typed ZnO layer on p-doped graphene and studied the ultraviolet (UV) photoresponse properties under a photocurrent (UV light on) and a UV light off.
TL;DR: An array of p-n junction heterostructures is fabricated by loading the surface of n-type semiconducting ZnO thin film with p-type CuO microclusters (μCs) for realization of uric acid biosensor without any external mediator.
Abstract: An array of p–n junction heterostructures is fabricated by loading the surface of n-type semiconducting ZnO thin film with p-type CuO microclusters (μCs) for realization of uric acid biosensor without any external mediator. Uricase is immobilized onto the prepared CuO/ZnO arrayed heterostructure in order to prepare the sensing electrode. The electrochemical performance of the prepared p - n junction based biosensor is investigated by means of cyclic voltammetry. A stable and well-defined peak corresponding to oxidation of uric acid is observed at a very low potential of 0.03 V in a mediator free solution. The largely decreased sensing potential may be attributed to the substantial enhancement of surface reaction kinetics in the formed p - n junction heterostructure due to built-in electric field which facilitate charge transport. A linear sensing response is observed over a range of 0.05–1.0 mM uric acid concentration with a high sensitivity of 1.74 mA/mM. Moreover, the prepared biosensor has good affinity towards uric acid (K m ∼ 0.05 mM) and possesses long shelf life ( >20 weeks). The low operating potential (0.03 V) of CuO/ZnO arrayed p - n heterojunction reduces the energy consumption of developed biosensor and efficiently minimizes interference from common oxidizable interferents, thereby, making the biosensor highly selective. Thus, CuO μCs/ZnO thin film based p - n junction heterostructure with internal electric field is a novel matrix for developing low powered biosensors to meet future energy demands.
TL;DR: In this article, a method to extract the junction temperature of high-voltage and high-power p-i-n diodes was proposed, where the swept-out charge during reverse recovery current fall time is affected by junction temperature variation, which makes the sweptout charge a possible thermo sensitive electrical parameter (TSEP).
Abstract: This paper proposes a method to extract the junction temperature of high-voltage and high-power p-i-n diodes. It is investigated that the swept-out charge during reverse recovery current fall time is affected by junction temperature variation, which makes the swept-out charge a possible thermo-sensitive electrical parameter (TSEP). Thanks to the specific package of high-power IGBT modules with p-i-n diodes, the swept-out charge of a p-i-n diode can be measured by the induced voltage v
eE
on the parasitic inductor L
eE
between Kelvin and power emitter terminals. In typical inductive half-bridge circuit, the comprehensive analysis of commutation between the upper p-i-n diode and lower enabled IGBT discloses the monotonic relationship among the reverse recovery charge, reverse current fall time, and junction temperature. A double pulse chopper circuit is used to validate the theoretical analysis. The experimental results show that the dependence between diode junction temperature and charge during the reverse recovery current fall time is approximately linear. A three-dimensional lookup table is calibrated and can be used to estimate the p-i-n diode junction operating temperature. Finally, an experimental comparison of four TSEPs for p-i-n diode is presented to verify the feasibility of the implementation of proposed TSEP.
TL;DR: P-n junctions in encapsulated graphene with a movable p-n interface are investigated with large quantum conductance oscillations on the order of e2/h which solely depend on the p- n junction position providing the first signature of isospin-defined conductance.
Abstract: At high magnetic fields the conductance of graphene is governed by the half-integer quantum Hall effect. By local electrostatic gating a p–n junction perpendicular to the graphene edges can be formed, along which quantum Hall channels copropagate. It has been predicted by Tworzidlo and co-workers that if only the lowest Landau level is filled on both sides of the junction, the conductance is determined by the valley (isospin) polarization at the edges and by the width of the flake. This effect remained hidden so far due to scattering between the channels copropagating along the p–n interface (equilibration). Here we investigate p–n junctions in encapsulated graphene with a movable p–n interface with which we are able to probe the edge-configuration of graphene flakes. We observe large quantum conductance oscillations on the order of e2/h which solely depend on the p–n junction position providing the first signature of isospin-defined conductance. Our experiments are underlined by quantum transport calcula...
TL;DR: An innovative approach to realize a p-n junction of topological surface states (TSS's) of a three-dimensional (3D) topological insulator (TI) with an atomically abrupt interface is demonstrated.
Abstract: Topological insulators (TI’s) are a new class of quantum matter with extraordinary surface electronic states, which bear great potential for spintronics and error-tolerant quantum computing. In order to put a TI into any practical use, these materials need to be fabricated into devices whose basic units are often p–n junctions. Interesting electronic properties of a ‘topological’ p–n junction were proposed theoretically such as the junction electronic state and the spin rectification. However, the fabrication of a lateral topological p–n junction has been challenging because of materials, process, and fundamental reasons. Here, we demonstrate an innovative approach to realize a p–n junction of topological surface states (TSS’s) of a three-dimensional (3D) topological insulator (TI) with an atomically abrupt interface. When a ultrathin Sb film is grown on a 3D TI of Bi2Se3 with a typical n-type TSS, the surface develops a strongly p-type TSS through the substantial hybridization between the 2D Sb film and ...
TL;DR: In this paper, the hot-carrier-induced damage of a gate dielectric was cured with Joule heat generated by the forward current of the p-n junction between the body and drain, for the first time.
Abstract: The hot-carrier-induced damage of a gate dielectric was cured with Joule heat generated by the forward current of the p-n junction between the body and drain, for the first time. The effective recovery voltage and pulse timewere optimized to cure the gate dielectricdamage produced by hot-carrier injection. Moreover, iterative damage and cyclic curing were experimentally demonstrated. Throughlow-frequency noise analyses, the degradationand recovery were verified by identifying trap density along the depth of the gate dielectric. Furthermore, this proposed method produced nearly the same recovery characteristics through source-to-body junction current in a short-channel device.
TL;DR: In this article, the authors reported the sharp switching behavior observed in an electrostatically controlled graphene nanoribbon p-n junction in pn and np biasing and demonstrated current modulation with a slope of 42mV/dec over five order of magnitude in drain current at 5k when the device is switched from nn to np configuration.
TL;DR: A photocatalytic heterojunction device of rutile TiO2 nanorod arrays based on a p-n silicon junction (TiO2@PN) and its full absorption of ultraviolet and visible light for synergistic photodegradation shows its promise in the solar-driven degradation of environmental pollution.
Abstract: Herein, we report a photocatalytic heterojunction device of rutile TiO2 nanorod arrays based on a p–n silicon junction (TiO2@PN) and its full absorption of ultraviolet and visible light for synergistic photodegradation. The fabricated TiO2@PN had excellent photocatalytic degradation of methyl orange (MO) under irradiation of a 300 W Xe lamp, and its pseudo-first-order rate constant k was 0.221 h−1, which was greatly higher than that for TiO2 nanorod arrays based on an n–p silicon junction (TiO2@NP, 0.078 h−1) and glass (TiO2@G, 0.032 h−1). The higher photocatalytic performance of TiO2@PN could be attributed to the fact that the photovoltage (PV) of the p–n junction promotes separation of the electron–hole pairs of the TiO2, and the holes are thus left within the TiO2 nanorods to produce a strong oxidant of hydroxyl radicals (˙OH). Moreover, this heterojunction device could be easily fabricated in a large size for easy recovery and recycling, which shows its promise in the solar-driven degradation of environmental pollution.
TL;DR: In this article, the average crystalline size of the ZnO nanomaterials were enhanced from 50nm to 70nm for the doping concentration of Sm 3+ ions in the lattices of Zn-O, since the charge transformation between the 4f electronic level of Sm3+ ions and conduction band of ZNO.
TL;DR: In this article, the authors showed that the presence of these pn-junctions can induce significant additional charge-carrier recombination, which affects the conversion efficiency of IBC cells through a reduction in fill factor and open-circuit voltage.
Abstract: Interdigitated back-contact (IBC) solar cells based on diffused crystalline silicon comprise a series of pn -junctions which border at the rear surface of the wafer. In this work, it is established that the presence of these pn -junctions can induce significant additional charge-carrier recombination, which affect the conversion efficiency of IBC cells through a reduction in fill factor and open-circuit voltage. Using specialized test structures with varying length of pn -junctions per area of solar cell (i.e., with varying junction density), the magnitude of the recombination at the pn -junction was determined. For nonpassivated rear surfaces, a second-diode recombination current density per unit of junction density J 02 of ∼61 nA·junction–1·cm–1 was measured, whereas for surfaces which were passivated by either SiN $_{x}$ or Al 2O3/SiN $_{x}$ , J 02 was reduced to ∼0.4 nA·junction–1·cm–1. Therefore, passivation of defects at the rear surface was proven to be vital in reducing this characteristic recombination current. Finally, by optimizing the p - and n -type dopant diffusion process recipes, J 02 recombination could be suppressed. The improved doping recipes led to an increase in conversion efficiency of industrial “mercury” IBC solar cells by ∼1% absolute.
TL;DR: In this article, the authors demonstrate silicon ridge waveguide photo-detectors capable of sub-bandgap light absorption and avalanche multiplication, which contain highly doped PN junction, where a strong electric field can generate the photon-assisted tunneling current for sub bandgap light incidence and amplify the generated photo-current by the avalanche multiplication effect.
Abstract: We demonstrate silicon ridge waveguide photo-detectors capable of sub-bandgap light absorption and avalanche multiplication. The proposed waveguide photo-detectors contain highly doped PN junction, where a strong electric field can generate the photon-assisted tunneling current for sub-bandgap light incidence and amplify the generated photo-current by the avalanche multiplication effect. The voltage-dependent sub-bandgap absorption coefficient and multiplication gain are experimentally evaluated for various doping configurations to find optimal photo-response with low dark currents. As a result, our representative silicon waveguide photo-detector gives sub-bandgap responsivities of ~10 and ~2 A/W under the applied reverse bias voltage of −8.3 V for near-infrared wavelengths of 1.31 and 1.52 μm, respectively. The voltage-dependent frequency photo-response is also demonstrated with theoretical verification.
TL;DR: The modulation of charge carrier concentration allows us to tune the Fermi level (E F) of graphene thanks to the low electronic density of states near the E F, and facilitates graphene to access state-of-the-art complimentary-metal-oxide-semiconductor (CMOS) technology.
Abstract: The modulation of charge carrier concentration allows us to tune the Fermi level (E F) of graphene thanks to the low electronic density of states near the E F. The introduced metal oxide thin films as well as the modified transfer process can elaborately maneuver the amounts of charge carrier concentration in graphene. The self-encapsulation provides a solution to overcome the stability issues of metal oxide hole dopants. We have manipulated systematic graphene p-n junction structures for electronic or photonic application-compatible doping methods with current semiconducting process technology. We have demonstrated the anticipated transport properties on the designed heterojunction devices with non-destructive doping methods. This mitigates the device architecture limitation imposed in previously known doping methods. Furthermore, we employed E F-modulated graphene source/drain (S/D) electrodes in a low dimensional transition metal dichalcogenide field effect transistor (TMDFET). We have succeeded in fulfilling n-type, ambipolar, or p-type field effect transistors (FETs) by moving around only the graphene work function. Besides, the graphene/transition metal dichalcogenide (TMD) junction in either both p- and n-type transistor reveals linear voltage dependence with the enhanced contact resistance. We accomplished the complete conversion of p-/n-channel transistors with S/D tunable electrodes. The E F modulation using metal oxide facilitates graphene to access state-of-the-art complimentary-metal-oxide-semiconductor (CMOS) technology.
TL;DR: In this paper, transparent, conducting p-La1−xSrxCrO3 epitaxial layers were deposited on Nb-doped SrTiO3(001) by oxygen-assisted molecular beam epitaxy to form structurally coherent p-n junctions.
Abstract: Transparent, conducting p-La1−xSrxCrO3 epitaxial layers were deposited on Nb-doped SrTiO3(001) by oxygen-assisted molecular beam epitaxy to form structurally coherent p-n junctions. X-ray photoelectron spectroscopy reveals a type II or “staggered” band alignment, with valence and conduction band offsets of 2.0 eV and 0.9 eV, respectively. Diodes fabricated from these heterojunctions exhibit rectifying behavior, and the I-V characteristics are different from those for traditional semiconductor p-n junctions. A rather large ideality factor is ascribed to the complex nature of the interface.
TL;DR: In this paper, the electro-refractive modulation of CVD grown single layer graphene placed on top of a silicon microring resonator biased using a polymer electrolyte gate was studied.
Abstract: Here in this work, we study the electro-refractive modulation of CVD grown single layer graphene placed on top of a silicon microring resonator biased using a polymer electrolyte gate. A voltage length product for a phase shift of π, VπL = 2.7 Vmm has been extracted, which is better compared to silicon depletion horizontal and interleaved pn junction type phase modulators and competitive with Silicon-Insulator-Silicon Capacitor modulators.