Showing papers on "Breakdown voltage published in 2013"
TL;DR: In this article, single-crystal gallium oxide (Ga2O3) metal-oxide-semiconductor field effect transistors were fabricated on a semi-insulating β-Ga 2O3 (010) substrate.
Abstract: Single-crystal gallium oxide (Ga2O3) metal-oxide-semiconductor field-effect transistors were fabricated on a semi-insulating β-Ga2O3 (010) substrate. A Sn-doped n-Ga2O3 channel layer was grown by molecular-beam epitaxy. Si-ion implantation doping was performed to source and drain electrode regions for obtaining low-resistance ohmic contacts. An Al2O3 gate dielectric film formed by atomic layer deposition passivated the device surface and significantly reduced gate leakage. The device with a gate length of 2 μm showed effective gate modulation of the drain current with an extremely low off-state drain leakage of less than a few pA/mm, leading to a high drain current on/off ratio of over ten orders of magnitude. A three-terminal off-state breakdown voltage of 370 V was achieved. Stable transistor operation was sustained at temperatures up to 250 °C.
544 citations
TL;DR: In this article, the authors fabricated gallium oxide (Ga2O3) Schottky barrier diodes using single-crystal substrates produced by the floating-zone method.
Abstract: We fabricated gallium oxide (Ga2O3) Schottky barrier diodes using β-Ga2O3 single-crystal substrates produced by the floating-zone method. The crystal quality of the substrates was excellent; the X-ray diffraction rocking curve peak had a full width at half-maximum of 32 arcsec, and the etch pit density was less than 1×104 cm-2. The devices exhibited good characteristics, such as an ideality factor close to unity and a reasonably high reverse breakdown voltage of about 150 V. The Schottky barrier height of the Pt/β-Ga2O3 interface was estimated to be 1.3-1.5 eV.
285 citations
TL;DR: In this paper, Schottky barrier diodes and metal-semiconductor field effect transistors (MESFETs) were demonstrated for the first time on β-Ga2O3 homoepitaxial layers.
235 citations
TL;DR: ZIF-8 films were deposited on silicon wafers and characterized to assess their potential as future insulators (low-κ dielectrics) in microelectronics Scanning electron microscopy and gas adsorption monitored by spectroscopic ellipsometry confirmed the good coalescence of the crystals, the absence of intergranular voids, and the hydrophobicity of the pores Mechanical properties were assessed by nanoindentation and tape tests, confirming sufficient rigidity for chip manufacturing processes and the good adhesion to the support as mentioned in this paper.
Abstract: ZIF-8 films were deposited on silicon wafers and characterized to assess their potential as future insulators (low-κ dielectrics) in microelectronics Scanning electron microscopy and gas adsorption monitored by spectroscopic ellipsometry confirmed the good coalescence of the crystals, the absence of intergranular voids, and the hydrophobicity of the pores Mechanical properties were assessed by nanoindentation and tape tests, confirming sufficient rigidity for chip manufacturing processes (elastic modulus >3 GPa) and the good adhesion to the support The dielectric constant was measured by impedance analysis at different frequencies and temperatures, indicating that κ was only 233 (±005) at 100 kHz, a result of low polarizability and density in the films Intensity voltage curves showed that the leakage current was only 10–8 A cm2 at 1 MV cm–1, and the breakdown voltage was above 2 MV cm–1 In conclusion, metal-organic framework ZIF-8 films were experimentally found to be promising candidates as low-κ
222 citations
TL;DR: In this paper, a 600-V normally-off SiNx/AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) is reported.
Abstract: In this letter, 600-V normally-OFF SiNx/AlGaN/GaN metal-insulator-semiconductor high-electron-mobility transistor (MIS-HEMT) is reported. Normally-OFF operation and low OFF-state gate leakage are obtained by using fluorine plasma ion implantation in conjunction with the adoption of a 17-nm SiNx thin film grown by plasma-enhanced chemical vapor deposition as the gate insulator. The normally-OFF MIS-HEMT exhibits a threshold voltage of +3.6 V, a drive current of 430 mA/mm at a gate bias of 14 V, a specific ON-resistance of 2.1 mΩ·cm2 and an OFF-state breakdown voltage of 604 V at a drain leakage current of 1 μA/mm with VGS=0 V, and the substrate grounded. Effective current collapse suppression is obtained by AlN/SiNx passivation as proved by high-speed pulsed I-V and low-speed high-voltage switching measurement results.
220 citations
TL;DR: In this article, vertical p-n diodes fabricated on pseudobulk gallium nitride (GaN) substrates are discussed, and the measured devices demonstrate breakdown voltages of 2600 V with a differential specific on-resistance of 2 mΩ cm2.
Abstract: In this paper, vertical p-n diodes fabricated on pseudobulk gallium nitride (GaN) substrates are discussed. The measured devices demonstrate breakdown voltages of 2600 V with a differential specific on-resistance of 2 mΩ cm2. This performance places these structures beyond the SiC theoretical limit on the power device figure of merit chart. Contrary to common belief, GaN devices do possess avalanche capability. The temperature coefficient of the breakdown voltage is positive, showing that the breakdown is indeed because of impact ionization and avalanche. This is an important property of the device for operation in inductive switching environments. Critical electric field and mobility parameters for epitaxial GaN layers grown on bulk GaN are extracted from electrical measurements. The reverse recovery time of the vertical GaN p-n diode is not discernible because it is limited by capacitance rather than minority carrier storage, and because of this its switching performance exceeds the highest speed silicon diode.
211 citations
TL;DR: In this article, a novel AlGaN/GaN-on-Si rectifier with a gated ohmic anode has been proposed to reduce the turn-on voltage without breakdown-voltage degradation.
Abstract: A novel AlGaN/GaN-on-Si rectifier with a gated ohmic anode has been proposed to reduce the turn-on voltage without breakdown-voltage degradation. The combination of an ohmic anode and a recessed Schottky gate is responsible for the low turn-on voltage and thus increases the forward current. In comparison with conventional Schottky diodes, the forward current at 1.5 V was increased by 2 to 3 times, whereas no breakdown-voltage degradation was observed. The proposed rectifier with an anode-to-cathode distance of 18 μm exhibited a turn-on voltage of 0.37 V, a forward current density of 92 mA/mm at 1.5 V, and a breakdown voltage of 1440 V.
116 citations
TL;DR: In this paper, the authors investigated the effect of the parasitic inductance of the circuit layout on the performance of parallel-connected normally ON silicon carbide JFETs and found that using a single gate circuit for the two mismatched JFs may improve the switching performance and therefore the distribution of the switching losses significantly.
Abstract: State-of-the-art silicon carbide switches have current ratings that are not sufficiently high to be used in high-power converters. It is, therefore, necessary to connect several switches in parallel in order to reach sufficient current capabilities. An investigation of parallel-connected normally ON silicon carbide JFETs is presented in this paper. The device parameters that play the most important role for the parallel connection are the pinch-off voltage, the gate-source reverse breakdown voltage, the spread in the on-state resistances, and the variations in static transfer characteristics of the devices. Moreover, it is experimentally shown that a fifth factor affecting the parallel connection of the devices is the parasitic inductances of the circuit layout. The temperature dependence of the gate-source reverse breakdown voltages is analyzed for two different designs of silicon carbide JFETs. If the spread in the pinch-off and gate-source reverse breakdown voltages is sufficiently large, there might be no possibility for a stable off-state operation of a pair of transistors without forcing one of the gate voltages to exceed the breakdown voltage. A solution to this problem using individual gate circuits for the JFETs is given. The switching performance of two pairs of parallel-connected devices with different combinations of parameters is compared employing two different gate-driver configurations. Three different circuit layouts are considered and the effect of the parasitic inductances is experimentally investigated. It is found that using a single gate circuit for the two mismatched JFETs may improve the switching performance and therefore the distribution of the switching losses significantly. Based on the measured switching losses, it is also clear that regardless of the design of the gate drivers, the lowest total switching losses for the devices are obtained when they are symmetrically placed.
111 citations
TL;DR: In this paper, a novel high-electron mobility transistor (HEMT) structure employing wider bandgap AlGaN for a channel layer, which is called Al-GaN channel HEMT, and investigated it.
Abstract: Enhanced performance of RF power modules is required in a next-generation information society. To satisfy these requirements, we designed a novel high-electron mobility transistor (HEMT) structure employing wider bandgap AlGaN for a channel layer, which we called AlGaN channel HEMT, and investigated it. The wider bandgap is more effective for higher voltage operation of HEMTs and contributes to the increase of output power in RF power modules. As a result, fabricated AlGaN channel HEMTs had much higher breakdown voltages than those of conventional GaN channel HEMTs with good pinchoff operation and sufficiently high drain current density without noticeable current collapse. Furthermore, specific on-state resistances of fabricated AlGaN channel HEMTs were competitive with the best values of reported GaN- and SiC-based devices with similar breakdown voltages. These results indicate that the proposed AlGaN channel HEMTs are very promising not only for an information-communication society but also in the power electronics field.
107 citations
TL;DR: In this article, the characteristics of Gallium Nitride (GaN) p-n junction diodes fabricated on free-standing GaN substrates with low specific on-resistance Ron and high breakdown voltage VB were described.
Abstract: In this letter, we describe the characteristics of Gallium Nitride (GaN) p–n junction diodes fabricated on free-standing GaN substrates with low specific on-resistance Ron and high breakdown voltage VB. The breakdown voltage of the diodes with the field-plate (FP) structure was over 3 kV, and the leakage current was low, i.e., in the range of 10-4 A/cm2. The specific on-resistance of the diodes of 60 µm diameter with the FP structure was 0.9 mΩcm2. Baliga's figure of merit (VB2/Ron) of 10 GW/cm2 is obtained. Although a certain number of dislocations were included in the device, these excellent results indicated a definite availability of this material system for power-device applications.
98 citations
TL;DR: An effective passivation technique that yields low off-state leakage and low current collapse simultaneously in highvoltage (600-V) AlGaN/GaN high-electron-mobility transistors (HEMTs) is reported in this article.
Abstract: An effective passivation technique that yields low off-state leakage and low current collapse simultaneously in high-voltage (600-V) AlGaN/GaN high-electron-mobility transistors (HEMTs) is reported in this letter. The passivation structure consists of an AlN/SiNx stack with 4-nm AlN deposited by plasma-enhanced atomic layer deposition and 50-nm SiNx deposited by PECVD. The AlN/ SiNx-passivated HEMTs with a gate-drain distance of 15 μm exhibit a high maximum drain current of 900 mA/mm, a low off-state current of 0.7 μA/mm at VDS = 600 V, and a steep subthreshold slope of 63 mV/dec. Compared with the static on-resistance of 1.3 mΩ·cm2, the dynamic on-resistance after high off-state drain bias stress at 650 V only increases to 2.1 mΩ·cm2. A high breakdown voltage of 632 V is achieved at a drain leakage current of 1 μA/mm .
TL;DR: In this paper, 1000-transistor-level monolithic circuit integration of sub-30nm gate-recessed E/D GaN high-electron-mobility transistors with fT and fmax above 300 GHz was reported.
Abstract: We report 1000-transistor-level monolithic circuit integration of sub-30-nm gate-recessed E/D GaN high-electron-mobility transistors with fT and fmax above 300 GHz. Simultaneous fT/fmax of 348/340 and 302/301 GHz for E- and D-mode devices, respectively, was measured, representing a 58% increase in fT compared with our previous report, due to improved management of RC parasitic delay. Three-terminal E- and D-mode breakdown voltage of 10.7 and 11.8 V, respectively, is limited by gate-drain breakdown.
TL;DR: In this article, a characterization of the application of atomic layer deposition (ALD) of hafnium dioxide (HfO2) and aluminum oxide (Al2O3), and plasma-enhanced chemical vapor deposition (PECVD) of silicon nitride (Si3N4) as metal-insulator-metal (MIM) capacitor dielectric for GaAs heterojunction bipolar transistor (HBT) technology was performed.
Abstract: Characterization was performed on the application of atomic layer deposition (ALD) of hafnium dioxide (HfO2) and aluminum oxide (Al2O3), and plasma-enhanced chemical vapor deposition (PECVD) of silicon nitride (Si3N4) as metal–insulator–metal (MIM) capacitor dielectric for GaAs heterojunction bipolar transistor (HBT) technology. The results show that the MIM capacitor with 62 nm of ALD HfO2 resulted in the highest capacitance density (2.67 fF/μm2), followed by capacitor with 59 nm of ALD Al2O3 (1.55 fF/μm2) and 63 nm of PECVD Si3N4 (0.92 fF/μm2). The breakdown voltage of the PECVD Si3N4 was measured to be 73 V, as compared to 34 V for ALD HfO2 and 41 V for Al2O3. The capacitor with Si3N4 dielectric was observed to have lower leakage current than both with Al2O3 and HfO2. As the temperature was increased from 25 to 150 °C, the breakdown voltage decreased and the leakage current increased for all three films, while the capacitance increased for the Al2O3 and HfO2. Additionally, the capacitance of the ALD Al...
TL;DR: In this article, a crack-free AlGaN/GaN high-electron-mobility transistors (HEMTs) are presented on a 200 mm Si substrate by metal-organic chemical vapor deposition (MOCVD).
Abstract: Crack-free AlGaN/GaN high-electron-mobility transistors (HEMTs) grown on a 200 mm Si substrate by metal–organic chemical vapor deposition (MOCVD) is presented. As grown epitaxial layers show good surface uniformity throughout the wafer. The AlGaN/GaN HEMT with the gate length of 1.5 µm exhibits a high drain current density of 856 mA/mm and a transconductance of 153 mS/mm. The 3.8-µm-thick device demonstrates a high breakdown voltage of 1.1 kV and a low specific on-resistance of 2.3 mΩ cm2 for the gate–drain spacing of 20 µm. The figure of merit of our device is calculated as 5.3×108 V2 Ω-1 cm-2.
TL;DR: In this paper, a self-terminating gate recess etching technique was proposed to fabricate normally off AlGaN/GaN MOSFETs, which exhibited a threshold voltage as high as 3.2 V with a maximum drain current over 200 mA/mm and a 60% increased breakdown voltage than that of the conventional high electron mobility transistors.
Abstract: A self-terminating gate recess etching technique is first proposed to fabricate normally off AlGaN/GaN MOSFET. The gate recess process includes a thermal oxidation of the AlGaN barrier layer for 40 min at 615°C followed by 45-min etching in potassium hydroxide solution at 70°C, which is found to be self-terminated at the AlGaN/GaN interface with negligible effect on the underlying GaN layer, manifesting itself easy to control, highly repeatable, and promising for industrialization. The fabricated device based on this technique with atomic layer deposition Al2O3 as gate insulator exhibits a threshold voltage as high as 3.2 V with a maximum drain current over 200 mA/mm and a 60% increased breakdown voltage than that of the conventional high electron mobility transistors.
TL;DR: In this paper, a selective Si diffusion approach is proposed to improve both the forward and reverse characteristics of AlGaN/GaN Schottky barrier diodes on Si substrates.
Abstract: In this letter, a selective Si diffusion approach is proposed to improve both the forward and reverse characteristics of AlGaN/GaN Schottky barrier diodes on Si substrates. The Si diffusion layer forms a dual Schottky barrier anode structure, which results in a low Schottky barrier portion to reduce the onset voltage VON from 1.3 to 1.0 V (23%). In the same process step, the selectively diffused Si is adopted in the cathode to reduce the ohmic contact resistance RC and improve the breakdown voltage VBK. A low RC of 0.21 Ω·mm and enhanced VBK up to 20% (from 1250 to 1500 V) are demonstrated, which can be attributed to the alleviated electric-field peaks around the alloy spikes beneath the ohmic contact.
17 Mar 2013
TL;DR: In this paper, the electrical performance of 4H-SiC Power MOSFETs is studied at temperatures from 93K to 473K. And the breakdown voltage is also measured down to 93K and found to increase monotonously with temperature.
Abstract: The electrical performance of 4H-SiC Power MOSFETs is studied at temperatures from 93K to 473K. With the decrease of operation temperature, the threshold voltage is found to increase linearly whereas the on-resistance shows a minimum value within the whole temperature range. The rapid increase of on-resistance at lower temperature is ascribed to the presence of large densities of interface traps at the SiC/SiO2 interface. In addition, the breakdown voltage is also measured down to 93K and found to increase monotonously with temperature. A set of parameters, determining the breakdown voltage of 4H-SiC MOSFET at different temperatures, is put forward in this paper, by fitting the experimental data.
TL;DR: In this paper, the effect of pulse rising time variable from 4ms to 100ns on plasma characteristics is investigated, and the experimental results confirm that the shorter the pulse rise time is, the more reactive the plasma is.
Abstract: Pulse direct current (dc) voltage with different pulse rising time trise have been used to generate atmospheric pressure non-equilibrium plasmas. However, no quantitative investigation has been reported on how the trise will affect the plasma characteristics. In this paper, the effect of pulse rising time variable from 4ms to 100ns on plasma characteristics is investigated. The experimental results show that, when the trise is reduced from 4ms to 140ns, the length of the plasma plume increases from less than 20mm to about 70mm, the peak value of the discharge current increases from about 0.2A to 1.3A. The corresponding breakdown voltage increase from less than 4kV to about 6 kV and the electron temperature increase from 1.25 eV to 1.55 eV. These results confirm that the shorter the pulse rising time is, the more reactive the plasma is.
TL;DR: In this article, it was found that at low concentration alumina nanoparticles exhibit uniform dispersion in epoxy nanocomposite while at higher concentration they depict aggregation of alumina particle.
TL;DR: In this paper, the vertical bulk (drain-bulk) current properties of analogous AlGaN/GaN hetero-structures molecular beam epitaxially grown on silicon, sapphire, and free-standing GaN (FS-GaN) have been evaluated.
Abstract: The vertical bulk (drain-bulk) current (Idb) properties of analogous AlGaN/GaN hetero-structures molecular beam epitaxially grown on silicon, sapphire, and free-standing GaN (FS-GaN) have been evaluated in this paper. The experimental Idb (25–300 °C) have been well reproduced with physical models based on a combination of Poole-Frenkel (trap assisted) and hopping (resistive) conduction mechanisms. The thermal activation energies (Ea), the (soft or destructive) vertical breakdown voltage (VB), and the effect of inverting the drain-bulk polarity have also been comparatively investigated. GaN-on-FS-GaN appears to adhere to the resistive mechanism (Ea = 0.35 eV at T = 25–300 °C; VB = 840 V), GaN-on-sapphire follows the trap assisted mechanism (Ea = 2.5 eV at T > 265 °C; VB > 1100 V), and the GaN-on-Si is well reproduced with a combination of the two mechanisms (Ea = 0.35 eV at T > 150 °C; VB = 420 V). Finally, the relationship between the vertical bulk current and the lateral AlGaN/GaN transistor leakage curr...
TL;DR: In this paper, the authors studied gas breakdown in micro/nanogaps at atmospheric pressure from low RF to high millimeter band, exhibiting a sharp decrease at a critical frequency, due to transition between the boundary and diffusion-controlled regimes, and a gradual increase at very high frequencies as a result of inefficient energy transfer by field.
Abstract: In this paper, we study gas breakdown in micro/nanogaps at atmospheric pressure from low RF to high millimeter band. For gaps larger than about 10 μm, the breakdown voltage agrees with macroscale vacuum experiments, exhibiting a sharp decrease at a critical frequency, due to transition between the boundary- and diffusion-controlled regimes, and a gradual increase at very high frequencies as a result of inefficient energy transfer by field. For sub-micron gaps, a much lower breakdown is obtained almost independent of frequency because of the dominance of field emission.
TL;DR: In this paper, the authors present the key features of single photon avalanche diode (SPAD) devices fabricated in a low voltage commercial 180-nm CMOS image sensor technology exhibiting very low dark count rate (DCR).
Abstract: This paper presents the key features of single photon avalanche diode (SPAD) devices fabricated in a low voltage commercial 180-nm CMOS image sensor technology exhibiting very low dark count rate (DCR). The measured DCR is <; 100 Hz at room temperature even for excess voltages above 2 V. The active junction of the SPAD measures 10 μm in diameter within a 24-μm test structure. The active region where Geiger avalanche occurs is determined by an implanted charge sheet. Edge avalanche is averted by utilizing a virtual guard ring, formed by the retrograde well profile. The design, measurements, and simulations of doping and electric field profiles that lead to such low DCR are reported and analyzed. The current-voltage characteristics and the temperature dependence of the breakdown voltage provide further, indirect evidence for the low DCR measured in the device. Thus, the key features of measured good SPADs are presented and are correlated with simulations that give physical insight on how to design high-performance SPADs.
TL;DR: In this article, the enhancement mode (E-mode) Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMTs) on Si.
Abstract: In this paper, we report on the enhancement-mode (E-mode) Al2O3/AlGaN/GaN metal-oxide-semiconductor high-electron mobility transistors (MOS-HEMTs) on Si. The E-mode operation is due to the negative charges in the atomic layer deposited Al2O3 layer. The unrecessed E-mode MOS-HEMTs exhibit high drain current density with a low specific ON-state resistance (RON,sp) of 0.7 mΩ·cm2. A low gate leakage current showed enhancements in the subthreshold characteristics such as ION/IOFF ratio ~108 and subthreshold slope of 75 mV/decade. This E-mode device showed good retention characteristics of threshold voltage upto 105 s. Furthermore, the E-mode MOS-HEMT exhibits an OFF-state breakdown voltage of 532 V for short gate-to-drain distance (Lgd=4 μm) that records a high power device figure of merit (FOM=BV2/RON,sp) value of 4×108 V2Ω-1cm-2.
TL;DR: In this paper, a 3D Schottky-barrier diodes (SBDs) based on a 3-D anode contact was proposed to reduce the reverse bias leakage current.
Abstract: We demonstrate ultralow leakage current AlGaN/GaN Schottky-barrier diodes (SBDs) based on a 3-D anode contact. In contrast to conventional AlGaN/GaN SBDs, this new device forms a Schottky contact directly to the 2-D electron gas (2-DEG) at the sidewalls of the 3-D anode structure to improve its turn-on characteristics. In addition, this device integrates an insulated trigate MOS structure to reduce its reverse-bias leakage current. By optimizing this new technology, we demonstrate SBDs with 3-D anode structures with turn-on voltage of 0.85 V, ON-resistance of 5.96 Ωmm and ideality factor of 1.27. The reverse-bias leakage current was significantly reduced by nearly four orders of magnitude, down to 260 pA/mm, with a breakdown voltage of up to 127 V for a distance of 1.5 μm between the cathode and anode electrodes. To the best of our knowledge, this is among the lowest leakage currents reported in lateral AlGaN/GaN SBDs fabricated on silicon substrate.
TL;DR: In this article, a combination of ex situ and in situ surface cleans was used to prepare the surface for deposition of ALE AlN, which showed improvements in 2-D electron gas sheet carrier density, gate leakage current, off-state drain leakage current and breakdown voltage.
Abstract: Enhancements in AlGaN/GaN high-electron-mobility transistor (HEMT) performance have been realized through ultrathin (4 nm) AlN passivation layers, formed by atomic layer epitaxy (ALE). A combination of ex situ and in situ surface cleans prepare the surface for deposition of ALE AlN. HEMTs passivated by high crystallinity AlN, grown at 500 °C, show improvements in 2-D electron gas sheet carrier density, gate leakage current, off-state drain leakage current, subthreshold slope, and breakdown voltage. In addition, degradation of dynamic on resistance during pulsed off-state voltage switching stress is suppressed by ~50% compared with HEMTs passivated by conventional plasma enhanced chemical vapor deposition SiNx.
TL;DR: In this paper, breakdown and withstand strengths of a synthetic ester, a natural ester and a mineral oil in a quasi-uniform sphere-to-sphere electric field under impulse voltages were investigated.
Abstract: This paper presents breakdown and withstand strengths of a synthetic ester, a natural ester and a mineral oil in a quasi-uniform sphere-to-sphere electric field under impulse voltages. The influences of impulse waveforms (lightning and switching), voltage polarities (positive and negative) and testing methods (rising-voltage, up-and-down and multiple-level) on the breakdown behaviour were investigated. The results indicated that breakdown voltages of both the ester liquids are comparable with those of the mineral oil under various test conditions. The withstand voltage at 1% breakdown probability was also obtained based on Weibull distribution fitting on the cumulative probability plot, which was built using the ~1000 impulse shots. It was found that the withstand voltages at 1% breakdown probability of the ester liquids are almost the same as that of the mineral oil. The results in this paper were further compared with other available test data in the literature. By comparing the performances between the ester liquids and the mineral oil, recommendations for insulation design were given to aid the application of ester liquids in high voltage large power transformers.
Journal Article•
TL;DR: In this article, a method for extracting an ionization coefficient from an arbitrary relationship between breakdown voltage and doping density in the Chynoweth's framework was proposed, and the breakdown field of diamond was estimated to depend on the doping density more than other materials.
Abstract: Although a high breakdown voltage or field is considered as a major advantage of diamond, there has been a large difference in breakdown voltages or fields of diamond devices in literature. Most of these apparently contradictory results did not correctly reflect material properties because of specific device designs, such as punch-through structure and insufficient edge termination. Once these data were removed, the remaining few results, including a record-high breakdown field of 20 MV/cm, were theoretically reproduced, exactly calculating ionization integrals based on the ionization coefficients that were obtained after compensating for possible errors involved in reported theoretical values. In this compensation, we newly developed a method for extracting an ionization coefficient from an arbitrary relationship between breakdown voltage and doping density in the Chynoweth's framework. The breakdown field of diamond was estimated to depend on the doping density more than other materials, and accordingly required to be compared at the same doping density. The figure of merit (FOM) of diamond devices, obtained using these breakdown data, was comparable to the FOMs of 4H-SiC and Wurtzite-GaN devices at room temperature, but was projected to be larger than the latter by more than one order of magnitude at higher temperatures about 300 °C. Considering the relatively undeveloped state of diamond technology, there is room for further enhancement of the diamond FOM, improving breakdown voltage and mobility. Through these investigations, junction breakdown was found to be initiated by electrons or holes in a p −-type or n −-type drift layer, respectively. The breakdown voltages in the two types of drift layers differed from each other in a strict sense but were practically the same. Hence, we do not need to care about the conduction type of drift layers, but should rather exactly calculate the ionization integral without approximating ionization coefficients by a power function of electric field as often done in Si devices. In order to facilitate this approach, we developed a method for simplifying the ionization integral, which method, together with the aforementioned method for extracting ionization coefficients, will help to promote the study on breakdown phenomena of all semiconductors.
TL;DR: In this article, a high-quality SiO2 deposition process using an inductively coupled plasma chemical vapor deposition system was developed for use as a gate oxide of AlGaN/GaN-on-Si metal-oxide-semiconductor heterostructure field effect transistor (MOSHFET) for power switching applications.
Abstract: We have developed a high-quality SiO2 deposition process using an inductively coupled plasma chemical vapor deposition system for use as a gate oxide of AlGaN/GaN-on-Si metal-oxide-semiconductor heterostructure field-effect transistor (MOSHFET) for power switching applications. A breakdown field of ~12 MV/cm was achieved using the optimized deposition conditions that were successfully applied in fabrication of the normally off AlGaN/GaN-on-Si MOSHFETs. The fabricated device exhibited excellent characteristics: a maximum drain current density of 375 mA/mm, a threshold voltage of 3 V, and a breakdown voltage of 820 V.
TL;DR: In this article, a heterojunction-free nanochannel GaN FinFET is proposed for high-performance and high-speed integrated circuits, which is a very promising candidate not only for high performance and high speed integrated circuits but also for high power applications.
Abstract: Heavily doped GaN nanochannel fin-shaped field-effect transistors (FinFETs) without heterojunction have been fabricated and characterized for the first time. Simplified pragmatical technology for GaN epitaxial growth and FinFET process was used to achieve nanodevices with a channel width from 40 to 100 nm and a gate length of 1 μm. They exhibit excellent on-state performance, such as maximum drain current of 670 mA/mm and maximum transconductance of 168 mS/mm. Record off-state performance was measured: extremely low leakage current of ~ 10-11 mA and source-drain breakdown voltage of ~280 V. The subthreshold slope of 68 mV/decade is close to the theoretical limit (60 mV/decade, so far achieved only in SOI MOSFETs) and leads to very high Ion/Ioff ratio of 108 - 109. The proposed heterojunction-free nanochannel GaN FinFET is a very promising candidate not only for high-performance and high-speed integrated circuits but also for high-power applications.