A5023714504- GaN-based semiconductor devices and materials
- Radio Frequency Integrated Circuit Design
- Semiconductor Quantum Structures and Devices
- Semiconductor materials and devices
- Ga2O3 and related materials
- Silicon Carbide Semiconductor Technologies
- Advancements in Semiconductor Devices and Circuit Design
- ZnO doping and properties
- Nanowire Synthesis and Applications
- Semiconductor materials and interfaces
- Metal and Thin Film Mechanics
- Advanced Power Amplifier Design
- Microwave Engineering and Waveguides
- Ferroelectric and Negative Capacitance Devices
- Advanced Semiconductor Detectors and Materials
- Integrated Circuits and Semiconductor Failure Analysis
University of California, Santa Barbara
2015-2024
Transphorm (United States)
2021-2022
Rochester Institute of Technology
2009-2015
This paper reports on state-of-the-art millimeter-wave power performance of N-polar GaN-based metal-insulator-semiconductor high-electron-mobility transistors at 30 and 94 GHz. The is enabled by our deep recess structure, whereby a GaN cap layer added in the access regions transistor to simultaneously enhance region conductivity while mitigating dc-to-RF dispersion. impact lateral scaling drain length examined using tradeoff between breakdown voltage small-signal gain. Load-pull measurements...
A novel N-Polar GaN cap (MIS)high electron mobility transistor demonstrating record 6.7-W/mm power density with an associated power-added efficiency of 14.4% at 94 GHz is presented. This state-of-the-art performance enabled by utilizing the inherent polarization fields in combination a 47.5-nm situ layer to simultaneously mitigate dispersion and improve access region conductivity. These excellent results build upon past work through use optimized device dimensions transition from sapphire...
This letter reports on the improvement of large-signal W-band power performance nitrogen-polar gallium nitride deep recess high electron mobility transistors with addition a 40-nm-thick ex-situ silicon passivation layer deposited by plasma enhanced chemical vapor deposition. The additional improves dispersion control allowing device to be operated at higher voltages. Continuous-wave load pull measurements performed 94 GHz 2×37.5 μm transistor demonstrated an in peak power-added efficiency...
Nitrogen polar (N-Polar) GaN high-electron-mobility transistors (HEMT) targeting high-voltage switching applications were fabricated on epi-layers grown by metal-organic chemical vapor deposition sapphire substrates. Devices demonstrated a combination of high breakdown voltage and low dynamic ON-resistance. Breakdown voltages over 2000 V observed with L <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> = 1 μm,...
In this article, N-polar GaN-on-sapphire deep-recess metal–insulator–semiconductor (MIS)-high-electron-mobility transistors (HEMTs) with a breakthrough performance at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${W}$ </tex-math></inline-formula> -band are presented. Compared prior GaN MIS-HEMTs, thin cap layer and atomic deposition (ALD) ruthenium (Ru) gate metallization were used along high-quality...
Though GaN HEMTs have primarily been used for power amplification, they are also well suited receiver applications. In the front-end of receivers, non-linearities, in particular third-order intermodulation products lead to in-band signal distortion. The distortion is dominated by transconductance and its derivatives. this paper, we report on N-polar MIS-HEMTs able simultaneously achieve high gain (12.7 dB) excellent linearity performance (OIP3/P <sub...
This letter reports on the W-band power performance of N-polar GaN deep recess MIS-high electron mobility transistors (HEMTs) using a new atomic layer deposition (ALD) ruthenium (Ru) gate metallization process. The structure is utilized to control DC-RF dispersion and increase conductivity in access regions. ALD Ru effectively fills narrow T-gate stems aiding realization shorter lengths with lower resistance than prior work. In this work, length was scaled down 48 nm, resulting demonstration...
We present results on 1200V GaN switches made with HEMTs sapphire substrates. These are fast-switching, low loss devices extending the high performance of to higher voltage levels. The insulating nature substrates can help extend rated and beyond, while simultaneously using a much thinner buffer layer compared GaN-on-Si for similar voltages. Using 70 mΩ GaN-on-sapphire 2-chip normally-off FET in TO-247 package, we obtained >99% efficiency 900:450V buck converter operating at 50kHz. die has R...
In this letter, the first four-finger (4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times25\,\,\mu \text{m}$ </tex-math></inline-formula> ) N-polar GaN high-electron-mobility transistor (HEMT) with an outstanding large signal performance of 712-mW (7.1 W/mm) 31.7% power-added efficiency (PAE) is demonstrated at 94 GHz. To best our knowledge, a record output power from single device cell in any...
In this letter, we report on Schottky barrier (SB) gate N-Polar GaN-on-sapphire deep recess high-electron-mobility transistors (HEMTs) with excellent dc, small signal and large performance. A device a length of 77 nm demonstrates very high extrinsic dc transconductance ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$ </tex-math></inline-formula> ) 917 mS/mm at notation="LaTeX">$V_{\mathbf {D}}$ 3...
Nitrogen polar SiN <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> /AlGaN/GaN/AlGaN metal- insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) with 28.6-nm equivalent GaN channel thickness grown by metal-organic chemical vapor deposition on sapphire substrate a high combination of current/power gain cutoff frequencies (f xmlns:xlink="http://www.w3.org/1999/xlink">T</sub> /f...
This work presents recent progress in the W-band (94 GHz) power performance of N-polar GaN deep recess HEMTs grown on sapphire substrates. While SiC has been substrate choice to achieve highest level performance, substrates are a lower cost alternative. In this we show that match device up 14 V with 5.1 W/mm output density. At 16 starts suffer from thermal effects but still demonstrated 5.5 an associated 20.6% power-added efficiency. also examines impact encapsulating low dielectric constant...
W-band power performance is reported on an N-polar GaN HEMT for the first time, resulting in a record output density any device sapphire substrate. This result achieved using deep recess MISHEMT structure grown by metal-organic chemical vapor deposition substrates. The key component this design addition of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in situ</i> unintentionally doped epitaxial passivation layer access regions transistor....
In this paper we extract a small-signal model of mm-wave deep-recess N-polar GaN MISHEMT exhibiting record 94 GHz power density. We show that certain existing methods for extrinsic parasitic extraction cannot be easily employed because the device design but an cold-bias method provides accurate extraction. The with pad layout parasitics is then validated gain measured at low input powers by loadpull system. factors impacting are analyzed to their origins and relative impact, giving guidance...
This article reports on the extraction of electron velocity as a function gate bias from N-polar GaN deep recess high-electron-mobility transistors (HEMTs) designed for mm-wave power amplification. Bias-dependent small-signal S-parameter measurements are used to obtain equivalent circuit parameters, which applied transit delay model. The model accounts fringing capacitance arrive at an associated with physical length. A peak 1.4 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Recently, III-V tunneling field effect transistors (TFET) for low voltage logic applications (<0.5V) have gained attention with the demonstration of sub-60 mV/dec. subthreshold slopes [1]. A key outstanding issue TFETs is limited drive currents, due to non-optimized carrier tunneling. With that in mind, aim this work map Esaki tunnel diode (TD) performance engineer TDs ultra high current densities while maintaining large peak-to-valley ratios (PVCR). This describes most comprehensive...
We report on the W-band power performance of N-polar GaN MISHEMTs demonstrating a record power-added efficiency (PAE) 27.8% while maintaining an excellent output density 3 W/mm and 7.4 dB peak gain at 94 GHz. To enable this performance, novel device technology is presented that utilizes advantages inverted polarization to mitigate dispersion improve access region conductivity through addition 47.5 nm in-situ cap layer. obtain these results past work has been extended pad layout optimization...
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...
The advantage of GaN is the capability producing amplifiers with high output power and efficiency. At microwave frequencies, this performance has been achieved; however, when transitioning device design into mm-wave efficiency HEMTs decrease. Traditionally, approach taken to develop Ka-band (30–40 GHz) devices modify a designed for lower frequency. By contrast, work modified N-polar deep recess HEMT developed W-band (94 GHz), improved in Ka-band. In Letter, we first report on improvement 30...
Combining excellent dispersion control with large breakdown voltage, deep recess N-polar GaN HEMT technology has demonstrated record high power densities [1] and efficiencies [2]–[3] from 2-finger devices <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$50-75\ \mu \mathrm{m}$</tex> gate peripheries at W-band. Employment of this in MMICs, however, will benefit larger periphery multi-finger to maximize the per unit cell thus reduce or even...
N-polar planar GaN metal-insulator-semiconductor high-electron-mobility transistors (MIS-HEMTs) grown by metal-organic chemical vapor deposition on sapphire substrate with a high combination of power cutoff frequency (f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> ) and three-terminal breakdown voltage (BV xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> as well decent DC-to-RF dispersion control are demonstrated. Compared to...
A novel device technology has been developed to enable the fabrication of high performance mm‐wave GaN electron mobility transistors (HEMTs) for solid‐state power amplifiers operating in W‐band. By utilising reverse polarisation N‐polar GaN, an in‐situ cap layer added access regions acts improve channel conductivity and reduces impact surface states on performance. low dispersion HEMT with 149 GHz peak f T 285 max demonstrated simultaneous efficiency output density 34.2% power‐added...
A W-band on-wafer passive load pull system constructed for the characterization of high power density N-polar GaN devices is presented. N-Polar GaN's large RF voltage swing enables densities but also increases match impedance which must be synthesized with limited tuning range. Increasing test cell gate width to decrease system's drive requirement. The tradeoff between these analyzed, showing that a can characterize wide range devices. This demonstrated measured data from an device...
This paper reports on the hot-carrier effects and semi-on-state behavior of nitrogen-polar GaN MIS-HEMTs at cryogenic temperatures (from 300 K down to 100 K). In (V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</sub> ≈ -2 V), holes are generated by impact ionization in high field region drain-side gate-edge. At room temperature, overcome SiN/AlGaN stack collected gate-terminal, resulting measurable hole gate-current (~11 nA/mm). Conversely,...