Showing papers on "Band gap published in 1996"
TL;DR: In this article, the authors focus on the properties of quantum dots and their ability to join the dots into complex assemblies creates many opportunities for scientific discovery, such as the ability of joining the dots to complex assemblies.
Abstract: Current research into semiconductor clusters is focused on the properties of quantum dots-fragments of semiconductor consisting of hundreds to many thousands of atoms-with the bulk bonding geometry and with surface states eliminated by enclosure in a material that has a larger band gap. Quantum dots exhibit strongly size-dependent optical and electrical properties. The ability to join the dots into complex assemblies creates many opportunities for scientific discovery.
10,737 citations
Patent•
01 Aug 1996TL;DR: In this article, a degenerate semiconductor material with a basic material having a bandgap between conduction band (11) and valence band (12) of electrons greater than 2.5 eV was presented.
Abstract: A semiconductor device includes a transparent switching element (1) with two connection electrodes (2, 3) of a transparent material and an interposed transparent channel region (4) of a semiconductor material provided with a transparent gate electrode (5) of a conductive material, separated from the channel region (4) by a transparent insulating layer (6). The semiconductor material is a degenerate semiconductor material with a basic material having a bandgap (10) between conduction band (11) and valence band (12) of electrons greater than 2.5 eV and a mobility of charge carriers greater than 10 cm2 /Vs provided with dopant atoms which form a fixed impurity energy level (13) adjacent or in the valence band (12) or conduction band (11) of the basic material. The degenerate semiconductor material is transparent because the absorption of visible light is not possible owing to the great bandgap (10), while also no absorption of visible light takes place through the impurity energy levels (13). The device is capable of comparatively fast switching.
1,065 citations
TL;DR: The corresponding generalized Kohn-Sham eigenvalue gaps are shown to incorporate part of the discontinuity D xc of the exchange-correlation potential of standard KohnSham theory, leading to band gaps far better than those of local-density approximation.
Abstract: As an alternative to the standard Kohn-Sham procedure, other exact realizations of density-functional theory ~generalized Kohn-Sham methods! are presented. The corresponding generalized Kohn-Sham eigenvalue gaps are shown to incorporate part of the discontinuity D xc of the exchange-correlation potential of standard KohnSham theory. As an example, a generalized Kohn-Sham procedure splitting the exchange contribution to the total energy into a screened, nonlocal and a local density component is considered. This method leads to band gaps far better than those of local-density approximation and to good structural properties for the materials Si, Ge, GaAs, InP, and InSb.
1,003 citations
TL;DR: In this paper, the authors derived the effective mass Hamiltonian for wurtzite semiconductors, including the strain effects, using the k-ensuremath{\cdot}p perturbation method, which is then checked with that derived using an invariant method based on the Pikus-Bir model.
Abstract: We derive the effective-mass Hamiltonian for wurtzite semiconductors, including the strain effects. This Hamiltonian provides a theoretical groundwork for calculating the electronic band structures and optical constants of bulk and quantum-well wurtzite semiconductors. We apply Kane's model to derive the band-edge energies and the optical momentum-matrix elements for strained wurtzite semiconductors. We then use the k\ensuremath{\cdot}p perturbation method to derive the effective-mass Hamiltonian, which is then checked with that derived using an invariant method based on the Pikus-Bir model. We obtain the band structure ${\mathit{A}}_{\mathit{i}}$ parameters in the group theoretical model explicitly in terms of the momentum-matrix elements. We also find the proper definitions of the important physical quantities used in both models and present analytical expressions for the valence-band dispersions, the effective masses, and the interband optical-transition momentum-matrix elements near the band edges, taking into account the strain effects. \textcopyright{} 1996 The American Physical Society.
924 citations
TL;DR: In this article, the authors demonstrate the successful integration of silicon-based visible light-emitting devices into a standard bipolar microelectronic circuit by exploiting the thermal and chemical stability of porous silicon.
Abstract: MICROELECTRONIC device integration has progressed to the point where complete 'systems-on-a-chip' have been realized1–3. Now that optoelectronics is becoming increasingly important for information and communication technologies, there is a need to develop optoelectronic devices that can be integrated with standard microelectronics. Conventional semiconductor technology is largely based on crystalline silicon, which (being an indirect bandgap semiconductor) is an inefficient light-emitting material. This has stimulated significant effort towards developing silicon-based optoelectronic components and, of the several strategies explored so far4,5, the use of porous silicon appears the most promising; porous silicon produces high-efficiency, room-temperature, visible photoluminescence6, and its material and optical properties have been studied in detail7,8. But the extreme reactivity and fragility of porous silicon have hitherto prevented its integration with conventional silicon processing technology. We have recently shown9,10 that the thermal and chemical stability of porous silicon can be greatly enhanced — while retaining desirable light-emitting and charge-transport properties — by partial oxidation. Here we take advantage of these improvements in material properties to demonstrate the successful integration of silicon-based visible light-emitting devices into a standard bipolar microelectronic circuit.
780 citations
TL;DR: In this article, a method to deduce energy distributions of defects in the band gap of a semiconductor by measuring the complex admittance of a junction is proposed, which consists of calculating the derivative of the junction capacitance with respect to the angular frequency of the signal corrected by a factor taking into account the band bending and the drop of the ac signal.
Abstract: A method to deduce energy distributions of defects in the band gap of a semiconductor by measuring the complex admittance of a junction is proposed. It consists of calculating the derivative of the junction capacitance with respect to the angular frequency of the ac signal corrected by a factor taking into account the band bending and the drop of the ac signal over the space charge region of the junction. Numerical modeling demonstrates that defect distributions in energy can be reconstructed by this method with high accuracy. Defect distributions of polycrystalline Cu(In,Ga)Se2 thin films are determined by this method from temperature dependent admittance measurements on heterojunctions of Cu(In,Ga)Se2 with ZnO that are used as efficient thin film solar cells.
688 citations
TL;DR: Angle-resolved photoemission experiments reveal evidence of an energy gap in the normal state excitation spectrum of the cuprate superconductor Bi2Sr2CaCu2O8+δ and the momentum dependence and magnitude closely resemble those of the dx2−y2 gap observed in the superconducting state.
Abstract: Angle-resolved photoemission experiments reveal evidence of an energy gap in the normal state excitation spectrum of the cuprate superconductor Bi2Sr2CaCu2O8+delta. This gap exists only in underdoped samples and closes around the doping level at which the superconducting transition temperature Tc is a maximum. The momentum dependence and magnitude of the gap closely resemble those of the dx2-y2 gap observed in the superconducting state. This observation is consistent with results from several other experimental techniques, which also indicate the presence of a gap in the normal state. Some possible theoretical explanations for this effect are reviewed.
653 citations
TL;DR: Solid-state polymer light-emitting electrochemical cells have been fabricated using thin films of blends of poly(1,4-phenylenevinylene) and poly(ethylene oxide) complexed with lithium trifluoromethanesulfonate, with an internal built-in potential close to the band gap of the redox-active conjugated polymer.
Abstract: Solid-state polymer light-emitting electrochemical cells have been fabricated using thin films of blends of poly(1,4-phenylenevinylene) and poly(ethylene oxide) complexed with lithium trifluoromethanesulfonate. The cells contain three layers: the polymer film (as the emissive layer) and indium-tin oxide and aluminum films as the two contact electrodes. When externally biased, the conjugated polymers are p-doped and n-doped on opposite sides of the polymer layer, and a light-emitting p-n junction is formed in between. The admixed polymer electrolyte provides the counterions and the ionic conductivity necessary for doping. The p-n junction is dynamic and reversible, with an internal built-in potential close to the band gap of the redox-active conjugated polymer (2.4 eV for PPV). Green light emitted from the p-n junction was observed with a turn-on voltage of about 2.4 V. The devices reached 8 cd/m(2) at 3 V and 100 cd/m(2) at 4 V, with an external quantum efficiency of 0.3-0.4% photons/electron. The response speed of these cells was around 1 s, depending on the diffusion of ions. Once the light-emitting junction had been formed, the subsequent operation had fast response (microsecond scale or faster) and was no longer diffusion-controlled.
587 citations
TL;DR: An analytic model is presented to describe the existence of photonic energy gaps in the propagation of surface plasmon polaritons on corrugated surfaces, designed to give direct access to expressions for the electromagnetic field and surface charge distributions associated with modes at the band edges thus allowing their physical character to be easily appreciated.
Abstract: We present an analytic model to describe the existence of photonic energy gaps in the propagation of surface plasmon polaritons on corrugated surfaces. We concentrate on elucidating the physical origin of the band gap, and accordingly we place strong emphasis on the physical reasoning and assumptions that we use. Our model is designed to give direct access to expressions for the electromagnetic field and surface charge distributions associated with modes at the band edges, thus allowing their physical character to be easily appreciated. Having established why a band gap occurs we then find expressions for the central position and width of the gap. We compare the results of our model for the gap width with those already in the literature, and find excellent agreement. Our results for the central position of the gap, notably the prediction that it should fall as the corrugation amplitude rises, contradicts one prediction made in the literature. We also reexamine the comparisons made in the literature between experiment and theory for the gap width, and find them inadequate because the theories have been compared to inappropriate experimental data. Consequently we present our own recent experimental data, enabling us to validate our theoretical results, in particular confirming our prediction that the central position of the gap falls as the corrugation amplitude is increased. The limitations of our model are discussed, as well as possible extensions and areas for future research.
527 citations
TL;DR: In this paper, quantum-confined InP nanocrystals from 20 to 50 A in diameter have been synthesized via the reaction of InCl3 and P(Si(CH3)3 )3 in trioctylphosphine oxide (TOPO) at elevated temperatures.
Abstract: Quantum-confined InP nanocrystals from 20 to 50 A in diameter have been synthesized via the reaction of InCl3 and P(Si(CH3)3)3 in trioctylphosphine oxide (TOPO) at elevated temperatures. The nanocrystals are highly crystalline, monodisperse, and soluble in various organic solvents. Improved size distributions have been obtained by size-selectively reprecipitating the nanocrystals. The UV/vis absorption spectra of the particles show the characteristic blue shift of the band gap of up to 1 eV due to quantum confinement, a moderately well-resolved first excitonic excited state, and, in some cases, the resolution of a higher excited state. Structurally, the nanocrystals are characterized with powder X-ray diffraction and transmission electron microscopy. Raman spectroscopy reveals TO and LO modes near the characteristic bulk InP positions as well a surface mode resulting from finite size. The Raman line widths, line positions, and relative intensities are all size-dependent . X-ray photoelectron spectroscopy ...
485 citations
TL;DR: InAs nanocrystal quantum dots have been prepared via colloidal chemical synthesis using the reaction of InCl3 and As[Si(CH3)3]3.
Abstract: InAs nanocrystal quantum dots have been prepared via colloidal chemical synthesis using the reaction of InCl3 and As[Si(CH3)3]3. Sizes ranging from 25 to 60 A in diameter are produced and isolated with size distributions of ±10%–15% in diameter. The nanocrystals are crystalline and generally spherical with surfaces passivated by trioctylphosphine giving them solubility in common organic solvents. The dots have been structurally characterized by transmission electron microscopy (TEM) and powder x‐ray diffraction (XRD) and the optical absorption and emission have been examined. Quantum confinement effects are evident with absorption onsets well to the blue of the bulk band gap and size dependent absorption and emission features. The emission is dominated by band edge luminescence. These quantum dots are particularly interesting as they provide an opportunity to make important comparisons with comparably sized InAs quantum dots synthesized by molecular beam epitaxy techniques.
TL;DR: In this paper, a linear relationship between bandgap and band edge was obtained for almost all the semiconductor oxides and it was pointed out that a bandgap energy higher than about 2.46 eV is necessary for water photolysis without bias voltage.
TL;DR: Electroabsorption measurements of built-in electric fields and internal photoemission measurements of Schottky barriers are reported to determine the charge transfer and single-particle energy gaps of the conjugated polymer poly[2-methoxy, 5-(2{prime}-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV).
Abstract: We report electroabsorption measurements of built-in electric fields and internal photoemission measurements of Schottky barriers to determine the charge transfer and single-particle energy gaps of the conjugated polymer poly[2-methoxy, 5-(2\ensuremath{'}-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). For MEH-PPV, with an exciton absorption peak of 2.25 eV, or results yield a single-particle energy gap of 2.45 eV and a charge transfer energy gap of at least 2.35 eV. Therefore the exciton binding energy is 0.2 eV and the bipolaron binding energy is less than 0.1 eV.
01 Jan 1996
TL;DR: An overview of the theoretical and experimental efforts in obtaining a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden, is presented in this paper.
Abstract: An overview of the theoretical and experimental efforts in obtaining a photonic band gap, a frequency band in three-dimensional dielectric structures in which electromagnetic waves are forbidden, is presented.
TL;DR: In this paper, the first observation of a full photonic band gap for surface modes was made, where it was shown that propagation is prohibited in all directions for modes with energies between 1.91 and 2.00 eV.
Abstract: We report the first observation of a full photonic band gap for surface modes. An experimental study has been made of the propagation of surface plasmon polaritons on a silver surface that is textured with a hexagonal array of dots with a periodicity of 300 nm. We find that propagation is prohibited in all directions for modes with energies between 1.91 and 2.00 eV.
TL;DR: In this article, the absolute energy of the valence and conduction band edges of a transparent nanocrystalline semiconductor electrode was determined using spectroelectrochemical techniques.
Abstract: Spectroelectrochemical techniques may be used to determine the absolute energy of the valence and conduction band edges of a transparent nanocrystalline semiconductor electrode. Such determinations have been made for ZnO (wurtzite) and TiO2 (anatase) electrodes constituted from nanocrystallites possessing average radii close to, and substantially larger than, the radius of a bound exciton in the corresponding bulk semiconductor. Electrodes constituted from crystallites whose radii are close to that of a bound exciton exhibit an onset for band gap absorption that is significantly blue-shifted. Those constituted from crystallites whose radii are substantially larger than that of a bound exciton exhibit an absorption onset characteristic of the bulk material. Knowing the absolute energies of band edges, the observed increase in band gap energy for electrodes constituted from confined nanocrystallites may be partitioned between the conduction and valence bands. A subsequent analysis permits determination of t...
TL;DR: The chemistry and electronic properties of interfaces formed between thin films of the archetype molecular organic semiconductor 3, 4, 9, 10 perylenetetracarboxylic dianhydride and reactive and nonreactive metals are investigated via synchrotron radiation photoemission spectroscopy.
Abstract: The chemistry and electronic properties of interfaces formed between thin films of the archetype molecular organic semiconductor 3, 4, 9, 10 perylenetetracarboxylic dianhydride (PTCDA) and reactive and nonreactive metals are investigated via synchrotron radiation photoemission spectroscopy. In, Al, Ti, and Sn react at room temperature with the anhydride group of the PTCDA molecule, producing heavily oxidized interface metal species and thick interfacial layers with a high density of states in the PTCDA band gap. The penetration of the reactive metal species in the PTCDA film is found to be inversely related to their first ionization energy. The noble metals Ag and Au form abrupt, unreacted interfaces. The chemical and structural results correlate well with the electrical properties of the interfaces that show Ohmic behavior with the reactive metal contacts and blocking characteristics with the noble metals. The Ohmic behavior of the reactive metal contacts is ascribed to carrier hopping and/or tunneling through the reaction-induced interface states. \textcopyright{} 1996 The American Physical Society.
TL;DR: In this paper, the electronic properties of self-assembled InAs/GaAs quantum dots are investigated theoretically and the microscopic distribution of the strain, valence-band mixing, and shape of the conduction band of InAs with strain are fully taken into account.
Abstract: The electronic properties of the self-assembled InAs/GaAs quantum dots are investigated theoretically. In our calculation the microscopic distribution of the strain, valence-band mixing, and the shape of the conduction band of InAs with strain are fully taken into account. New states are brought to light and their status in the framework of established approximate models of the electronic structure is critically examined.
TL;DR: The characteristics of the transport of photogenerated electrons through electrodes consisting of nanometer-size Ti${\mathrm{O}}_{2}$ particles were investigated by intensity modulated photocurrent spectroscopy.
Abstract: The characteristics of the transport of photogenerated electrons through electrodes consisting of nanometer-size Ti${\mathrm{O}}_{2}$ particles were investigated by intensity modulated photocurrent spectroscopy. Electronic transport is controlled by trapping and detrapping of photogenerated electrons in interfacial bandgap states, distributed in energy. The localization time of a trapped electron is controlled by the steady-state light intensity and interfacial kinetics.
TL;DR: In this paper, a two-dimensional photonic band structure based on macroporous silicon with a gap common to both polarizations and centered at 5 μm was fabricated, and a triangular lattice of circular air rods with a lattice constant of 2.3μm was etched 75 μm deep in an n-type silicon substrate by electrochemical pore formation in hydrofluoric acid.
Abstract: We have fabricated a two‐dimensional photonic band structure based on macroporous silicon with a gap common to both polarizations and centered at 5 μm. A triangular lattice of circular air rods with a lattice constant of 2.3 μm was etched 75 μm deep in an n‐type silicon substrate by electrochemical pore formation in hydrofluoric acid. The porous layer was then micromechanically structured in such a way that 200 μm thick free‐standing bars of porous material were left over on the silicon substrate. These bars were then used for measuring the transmission of the photonic lattice. The results showed an excellent agreement with the theoretically calculated structure.
TL;DR: In this article, thin-film solar cells have been fabricated from Cu(InGa)Se2 films which were deposited by four-source elemental evaporation with [Ga]/([In]+[Ga]) from 0.27 to 0.69 corresponding to a band gap from 1.16 to 1.45 eV.
Abstract: Thin‐film solar cells have been fabricated from Cu(InGa)Se2 films which were deposited by four‐source elemental evaporation with [Ga]/([In]+[Ga]) from 0.27 to 0.69 corresponding to a band gap from 1.16 to 1.45 eV. The films were intentionally deposited with no grading of the Ga and In to avoid gradients in their electrical and optical properties. X‐ray diffraction, energy‐dispersive x‐ray spectroscopy, and Auger electron spectroscopy show that the films have uniform composition with no change in structure and morphology. Glass/Mo/Cu(InGa)Se2/CdS/ZnO devices have open‐circuit voltage increasing over the entire band gap range to 788 mV and 15% total area efficiency for band gap less than 1.3 eV, or [Ga]/([In]+[Ga]) less than 0.5. A decrease in device efficiency with higher Ga content is caused primarily by a lower fill factor. Analysis of current–voltage and quantum efficiency measurements show that this results from a voltage‐dependent current collection.
TL;DR: In this paper, the authors discuss improvement in film properties as a function of growth chemistry and focus on MOCVD precursors used specifically for the growth of group III (Al, Ga, In) nitride films.
Abstract: The AlGaInN quaternary alloy system is uniquely suited for numerous device applications because the bandgap can be varied from 1.9 to 6.2 eV by changing the alloy composition. Growth of epitaxial device-quality group III (Al, Ga, In) nitride films has been hindered by a lack of suitably lattice matched substrates, the large equilibrium dissociation pressure of N2 from the nitrides at typical growth temperatures, and predeposition reactions in the commonly employed metal−organic chemical vapor (MOCVD) precursors. The most successful films have been grown at temperatures in excess of 900 °C by MOCVD. However, high growth temperatures may limit compatibility and incorporation of group III nitrides with existing fabrication technologies and devices. Attempts to lower deposition temperature include activated nitrogen sources and alternative precursors. This review will discuss improvement in film properties as a function of growth chemistry and will focus on MOCVD precursors used specifically for the growth of...
TL;DR: In this paper, the electronic structure of SiC/SiO2 interfaces was studied for different SiC polytypes (3C, 4H, 6H, 15R) using internal photoemission of electrons from the semiconductor into the oxide.
Abstract: The electronic structure of SiC/SiO2 interfaces was studied for different SiC polytypes (3C, 4H, 6H, 15R) using internal photoemission of electrons from the semiconductor into the oxide. The top of the SiC valence band is located 6 eV below the oxide conduction band edge in all the investigated polytypes, while the conduction band offset at the interface depends on the band gap of the particular SiC polytype. In the energy range up to 1.5 eV above the top of the SiC valence band, interface states were found. Their electron spectrum is similar to that of sp2‐bonded carbon clusters in diamond‐like a‐C:H films suggesting the presence of elemental carbon at the SiC/SiO2 interfaces.
TL;DR: Using a finite-difference time-domain method, the band-structure and transmission properties of three-dimensional metallodielectric photonic crystals are studied and partial gaps are predicted in the fcc lattice, in excellent agreement with recent experiments.
Abstract: Using a finite-difference time-domain method, we study the band-structure and transmission properties of three-dimensional metallodielectric photonic crystals The metallodielectric crystals are modeled as perfect electrical conducting objects embedded in dielectric media We investigate two different lattice geometries: the face-centered-cubic (fcc) lattice and the diamond lattice Partial gaps are predicted in the fcc lattice, in excellent agreement with recent experiments Complete gaps are found in a diamond lattice of isolated metal spheres The gaps appear between the second and third bands and their sizes can be larger than 60% when the radius of the spheres exceeds 21% of the cubic unit cell size A possible fabrication scheme for this structure is proposed and transmission calculations are performed \textcopyright{} 1996 The American Physical Society
TL;DR: In this paper, a band gap analysis of the Ln2O3 series of rare earth oxides, sulphides and selenides of the type ln2X3 is presented.
TL;DR: Crystal symmetry reduction opens up new ways for engineering photonic gaps by reducing the structure symmetry in two-dimensional square and honeycomb lattices of circular cross-section rods.
Abstract: Absolute photonic band gaps in two-dimensional square and honeycomb lattices of circular cross-section rods can be increased by reducing the structure symmetry. The addition of a smaller diameter rod into the center of each lattice unit cell lifts band degeneracies to create significantly larger band gaps. Symmetry breaking is most effective at filling fractions near those which produce absolute band gaps for the original lattice. Rod diameter ratios in the range 0.1–0.2 yield the greatest improvement in absolute gap size. Crystal symmetry reduction opens up new ways for engineering photonic gaps.
TL;DR: In this paper, the interface properties of Ga2O3-GaAs structures fabricated using in situ multiple-chamber molecular beam epitaxy have been investigated, where oxide films were deposited on clean, atomically ordered (100) GaAs surfaces at ≂600°C by electron-beam evaporation using a Gd3Ga5O12 single-crystal source.
Abstract: Interface properties of Ga2O3–GaAs structures fabricated using in situ multiple‐chamber molecular beam epitaxy have been investigated. The oxide films were deposited on clean, atomically ordered (100) GaAs surfaces at ≂600 °C by electron‐beam evaporation using a Gd3Ga5O12 single‐crystal source. Metal–insulator–semiconductor structures have been fabricated in order to characterize the Ga2O3–GaAs interface by capacitance–voltage measurements in quasistatic mode and at frequencies between 100 Hz and 1 MHz. The formation of inversion layers in both n and p‐type GaAs has been clearly established. Using the quasistatic/high frequency technique, the interface state density has been derived as a function of band gap energy and a midgap interface state density in the mid 1010 cm−2 eV−1 range has been inferred. Charge trapping in the oxide has been revealed as the dominant trapping mechanism.
TL;DR: In this paper, band-structure calculations, semi-empirical as well as ab initio, have been applied to study the electronic band gap of the new exotic natural low-dimensional MX systems (where M = Pb or Sn and X = I, Br or Cl).
Abstract: Band-structure calculations, semiempirical as well as ab initio, have been applied to study the electronic band gap of the new exotic natural low-dimensional MX systems (where M = Pb or Sn and X = I, Br or Cl). Moreover, variational calculations are employed to calculate the excitonic binding energies, whose amplification is due not only to the quantum confinement of the excitons but also to a dielectric enhancement effect. A single set of semiempirical parameters is sought to describe the materials; comparison of the calculations with experimental data shows this to be successful in the case of the PbI- and PbBr-containing compounds. .
PARC1
TL;DR: In this paper, the authors present a low-energy inversion domain boundary in which each atom remains fourfold coordinated without the formation of Ga-Ga or N-N bonds, denoted IDB*, which does not induce electronic states in the band gap and would therefore not adversely impact photoluminescence efficiency.
Abstract: We present first-principles calculations of domain wall energies for inversion domain boundaries and stacking mismatch boundaries in GaN. We find a low-energy inversion domain boundary in which each atom remains fourfold coordinated without the formation of Ga-Ga or N-N bonds. This boundary, denoted IDB*, does not induce electronic states in the band gap and would therefore not adversely impact photoluminescence efficiency. The stacking mismatch boundary has a higher formation energy than IDB*, and gives rise to occupied N-derived interface states in the band gap.
TL;DR: In this article, the minority-carrier surface recombination velocity of n-type silicon, Sp, was analyzed using photoconductance decay measurements of the recombination currents corresponding to different phosphorus diffusions, including oxide-, unpassivated, and metal-coated surfaces.
Abstract: New experimental data for the minority‐carrier surface recombination velocity of n‐type silicon, Sp, are reported. The data, obtained from photoconductance decay measurements of the recombination currents corresponding to different phosphorus diffusions, include oxide‐passivated, unpassivated and metal‐coated surfaces. For the passivated case, Sp increases linearly with surface dopant density, ND, for dopant densities higher than 1×1018 cm−3, while for unpassivated (bare) and for metal‐coated silicon Sp remains essentially constant, at about 2×105 cm/s and 3×106 cm/s, respectively. The experiments also allow for a determination of the apparent energy bandgap narrowing as a function of dopant density, ΔEgapp=14 meV [ln(ND/1.4×1017 cm−3)]. These surface recombination velocity and ΔEgapp data form, together with the dependences of minority‐carrier lifetime, τp, and mobility, μp, used in the analysis, a consistent set of parameters that fully characterize highly doped n‐type silicon.