The valence-band discontinuity at a wurtzite GaN/AlN(0001) heterojunction is measured by x-ray photoemission spectroscopy. method first measures the core level binding energies with respect to maximum in both GaN and AlN bulk films. precise location of determined aligning prominent features spectrum calculated densities states. Tables relative are reported for AlN. Subsequent measurements separations between Ga Al levels thin overlayers film grown on vice versa yield ΔEV=0.8±0.3 eV standard...

In this letter, we report on high breakdown voltage in situ oxide, GaN interlayer-based vertical trench MOSFETs (OG-FETs) bulk substrates. Following our previous work OG-FETs sapphire, utilizing a low damage gate-trench etch and using substrates, of 990 V with an ON-resistance 2.6 mQ · cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , was achieved. Without edge termination, field 1.6 MV/cm achieved these devices.

A normally OFF trench current aperture vertical electron transistor (CAVET) was designed and successfully fabricated with Mg-doped p-GaN blocking layers. The buried GaN activated using a postregrowth annealing process. source-to-drain body diode showed an excellent p-n junction characteristics, over 1 kV, sustaining maximum electric field of 3.8 MV/cm. Three-terminal breakdown voltages trench-CAVETs, measured up to 225 V, were limited by dielectric breakdown. This paper highlights the...

We report epitaxial GaN layers grown on 6H-SiC (0001) substrates. A two stage substrate preparation procedure is described which effectively removes oxygen from the SiC surface without need of elaborate high temperature processing. In first step, dangling Si bonds are hydrogen passivated using a HF dip before introduction into vacuum. Second, treated with plasma reducing amount oxygen-carbon bonding to below x-ray photoemission detection limit. Upon heating in molecular beam epitaxy (MBE)...

In this letter, we report a high-voltage metalinsulator-semiconductor gate trench current aperture vertical electron transistor using metal-organic chemical vapor deposition regrown AlGaN/GaN as the channel and in-situ Si <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> N xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> dielectric. The device had high breakdown voltage of 880 V low R...

In this letter, a novel device design to achieve both low ON-resistance and enhancement mode operation in vertical GaN FET is demonstrated. the traditional trench MOSFET structure, dielectric deposited on an n-p-n trenched structure channel forms via p-GaN inversion at dielectric/p-GaN interface. However, results relatively high due poor electron mobility channel. By changing include metal-organic chemical vapor deposition (MOCVD)-regrown Un-intentionally Doped (UID)-GaN interlayer followed...

A normally off (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">th</sub> = 4.7 V) vertical GaN OG-FET with a 10 nm UID-GaN channel interlayer and 50 in-situ Al xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gate dielectric has been successfully demonstrated scaled for higher current operation. By using novel double field-plated structure mitigating peak electric field, high off-state...

We present a large-area in-situ oxide, GaN interlayer-based vertical trench MOSFET (OG-FET) with metal organic chemical vapor deposition regrown 10-nm unintentional-doped-GaN interlayer as the channel and 50-nm Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> gate dielectric. The threshold voltage of device on bulk substrate was 1 V measured at I...

The effects of the Ga 3d semicore levels on electronic structure GaN are discussed. While band-structure theory using local-density approximation predicts these states to overlap with N 2s band and have important total energy, x-ray photoelectron spectroscopy (XPS) shows that they occur \ensuremath{\sim}3 eV below band. This apparent discrepancy is resolved by means a so-called \ensuremath{\Delta} SCF or difference self-consistent-fields calculation, in which binding energy calculated as...

Abstract GaN trench-gate MOSFETs with m - and a -plane-oriented sidewall channels were fabricated characterized. The MOSFET performance depended strongly on the sidewall-MOS-channel plane orientation. MOS channel devices demonstrated higher mobility, current density, lower sub-threshold slope, hysteresis similar threshold voltage on–off ratio compared to -plane devices. These results indicate that orienting toward would allow for better on-state characteristics while maintaining off-state...

In this letter, a GaN-based current aperture vertical electron transistor (CAVET) with p-type gate layer and an implantation-based blocking structure is presented. The devices measured showed breakdown voltage of 450 V no dispersion. factors limiting higher voltages in these were carefully studied discussed. grown on sapphire relied box-shaped Mg implanted scheme. This the first demonstration CAVET, respectable on-state characteristics.

Gate dielectricplays an integral role in advancing the performance and reliability of GaN-based transistors. Si-alloying aluminum oxide (Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> ) dielectrics have been shown to provide a promising route improve gate dielectric properties GaN. In this letter, we report on first demonstration GaN FET with silicon (AlSiO) as dielectric. Vertical...

In this paper, we report the successful demonstration of current aperture vertical electron transistors (CAVETs) obtained by using a novel implantation-based compensation method to achieve conductive aperture. This innovation leads first "regrowth-free" CAVETs. Two gallium nitride (GaN) CAVETs were fabricated ion-implantation-compensated regions, both with Mg-doped p-GaN as currentblocking layers (CBLs). The regions formed implanting Si into CBL. one CAVET samples, Si-implantation-based was...

This letter reports on the dynamic <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$R_{\text{ON}}$ </tex-math></inline-formula> performance of large-area GaN vertical trench MOSFETs (OG-FETs) fabricated bulk substrates. OG-FETs demonstrated excellent DC with a breakdown voltage 900 V and 4.1 notation="LaTeX">$\Omega$ (8.2 notation="LaTeX">$\text{m}\Omega \cdot \text {cm}^{2}$ ). However, damage to sidewalls...

Low temperature (LT) flow modulation epitaxy (FME) or “pulsed” growth was successfully used to prevent magnesium from Metalorganic Chemical Vapor Deposition (MOCVD) grown p-GaN:Mg layers riding into subsequently deposited n-type layers. Mg concentration in the subsequent lowered ∼1 × 1018 cm−3 for a medium at 950 °C 1016 low 700 via FME. The slope of drop FME sample 20 nm/dec—the lowest ever demonstrated by MOCVD. For on implanted GaN layers, regrowth ∼10 nm/dec compared &amp;gt;120 high...

Nitrogen polar (N-Polar) GaN high-electron mobility transistors (HEMT) targeting high efficiency in millimeter wave power amplification applications were fabricated on epitaxial layers grown by plasma assisted molecular beam epitaxy (PAMBE) on-axis semi-insulating bulk substrates. On-state current density of ~1 A mm−1 was observed with L G = 0.75 μm, GS 0.5 μm and GD 3.75 μm. In a deep class AB mode operation, devices structures these substrates demonstrated 60% higher electron channel...

A simple technique for tuning the work function of molybdenum (Mo) gate material over a wide range (4.5 V-4.9 V) is investigated. Ultra-low energy (/spl les/3 keV) Ar/sup +/ and N/sup ion implantation used to selectively induce structural and/or chemical changes in Mo films. These are shown directly affect function, so that it can be adjusted by adjusting implant parameters annealing conditions. The mechanism behind this phenomenon investigated using X-ray diffraction (XRD) photoelectron...

An electro-thermal co-design study has been performed on vertical GaN transistors (oxide, interlayer based trench MOSFETs; OG-FETs). Vertical (GaN-on-GaN) and quasi (GaN-on-sapphire) devices were investigated. showed a 60% lower device peak temperature rise as compared to the quasi-vertical OG-FETs. Using simulation, internal electric field heat generation distributions within OG-FETs analyzed. The of hexagonal honeycomb structured scaled array was characterized using thermoreflectance...

Controlled n-type doping down to 2 × 1015 cm−3 was achieved in GaN grown on sapphire by MOCVD balancing the Si with respect background carbon and oxygen levels. A dopant level of ∼1 1016 displayed a very high mobility 899 cm2 V−1 s−1. High electron drift layer leads low resistance current densities without compromising any other properties device. Schottky diodes processed these layers showed Ron values, while p–n display reverse breakdown voltages excess 1000 V for 8 μm thick cm−3.

In recent years, GaN trench MOSFETs have been actively investigated to achieve low on-resistance and high breakdown voltage [1-8]. The absence of a JFET region makes the MOSFET favorable device structure reduce on-resistance. However, poor (electron) channel mobility in lead increased resistance. This could potentially result reliability issues and/or as large gate bias is needed our previous works, we demonstrated novel design (OG-FET), where enhanced was obtained by inserting MOCVD-regrown...

GaN lateral transistors (HEMTs) continue to penetrate the power electronics market demonstrating excellent performance in medium applications. However, for applications 10kW and higher, vertical devices are preferred over one, since former offers higher current densities. To date, several different transistor structures have been proposed reported, such as in-situ oxide based trench MOSFET with an undoped interlayer a channel (OGFET) [1, 2], aperture electron (CAVETs) [3, 4], junction field...

In this letter, we have examined the impact of trench dimensions on breakdown voltage and ON-resistance MOSFETs fabricated sapphire bulk GaN substrates. Contrary to simulation studies, decreased with an increase in devices However, such dependence was not observed substrates same area. The trend associated equivalently reduced number dislocations per device These results give insight into how could affect power MOSFETs.

In this study we explored p-type δ-doping for the deposition of N-polar p-GaN films at 900 °C, application in device structures containing high composition active layers. Various process parameters were investigated, including duration and molar flow Mg precursor during each pulse as well period. The results compared to those obtained layers grown using continuous doping. As period was reduced from 25 5 nm, bulk resistivity decreased 6.8 2.8 cm. p-layer rose with increasing [Mg] independent...

GaN is one of the best suited materials for high-power devices due to its superior material properties such as high breakdown field, wide band gap and saturation drift velocity. Consequently, power have gained increased attention in recent years. Numerous vertical transistors been demonstrated past few years [1-4]. One preferred device designs trench MOSFET. In traditional MOSFET structure [2-4], channel forms via p-GaN inversion at dielectric/p-GaN interface resulting a relatively...