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Title: Al 0.85Ga 0.15N/Al 0.70Ga 0.30N High Electron Mobility Transistors with Schottky Gates and Large On/Off Current Ratio over Temperature

Abstract

AlGaN-channel high electron mobility transistors (HEMTs) are among a class of ultra wide-bandgap transistors that are promising candidates for RF and power applications. Long-channel Al xGa 1-xN HEMTs with x = 0.7 in the channel have been built and evaluated across the -50°C to +200°C temperature range. These devices achieved room temperature drain current as high as 46 mA/mm and were absent of gate leakage until the gate diode forward bias turn-on at ~2.8 V, with a modest -2.2 V threshold voltage. A very large I on/I off current ratio, of 8 × 10 9 was demonstrated. A near ideal subthreshold slope that is just 35% higher than the theoretical limit across the temperature range was characterized. The ohmic contact characteristics were rectifying from -50°C to +50°C and became nearly linear at temperatures above 100°C. An activation energy of 0.55 eV dictates the temperature dependence of off-state leakage.

Authors:
 [1];  [1];  [1];  [1];  [1];  [1];  [1]; ORCiD logo [1]
  1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Publication Date:
Research Org.:
Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1414439
Report Number(s):
SAND-2017-13486J
Journal ID: ISSN 2162-8769; 659496
Grant/Contract Number:
AC04-94AL85000; NA0003525
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
ECS Journal of Solid State Science and Technology
Additional Journal Information:
Journal Volume: 6; Journal Issue: 12; Journal ID: ISSN 2162-8769
Publisher:
Electrochemical Society
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; HEMT; high electron mobility transistor; Ultra-wide-bandgap

Citation Formats

Baca, Albert G., Klein, Brianna A., Allerman, Andrew A., Armstrong, Andrew M., Douglas, Erica A., Stephenson, Chad A., Fortune, Torben R., and Kaplar, Robert J. Al0.85Ga0.15N/Al0.70Ga0.30N High Electron Mobility Transistors with Schottky Gates and Large On/Off Current Ratio over Temperature. United States: N. p., 2017. Web. doi:10.1149/2.0231712jss.
Baca, Albert G., Klein, Brianna A., Allerman, Andrew A., Armstrong, Andrew M., Douglas, Erica A., Stephenson, Chad A., Fortune, Torben R., & Kaplar, Robert J. Al0.85Ga0.15N/Al0.70Ga0.30N High Electron Mobility Transistors with Schottky Gates and Large On/Off Current Ratio over Temperature. United States. doi:10.1149/2.0231712jss.
Baca, Albert G., Klein, Brianna A., Allerman, Andrew A., Armstrong, Andrew M., Douglas, Erica A., Stephenson, Chad A., Fortune, Torben R., and Kaplar, Robert J. 2017. "Al0.85Ga0.15N/Al0.70Ga0.30N High Electron Mobility Transistors with Schottky Gates and Large On/Off Current Ratio over Temperature". United States. doi:10.1149/2.0231712jss. https://www.osti.gov/servlets/purl/1414439.
@article{osti_1414439,
title = {Al0.85Ga0.15N/Al0.70Ga0.30N High Electron Mobility Transistors with Schottky Gates and Large On/Off Current Ratio over Temperature},
author = {Baca, Albert G. and Klein, Brianna A. and Allerman, Andrew A. and Armstrong, Andrew M. and Douglas, Erica A. and Stephenson, Chad A. and Fortune, Torben R. and Kaplar, Robert J.},
abstractNote = {AlGaN-channel high electron mobility transistors (HEMTs) are among a class of ultra wide-bandgap transistors that are promising candidates for RF and power applications. Long-channel AlxGa1-xN HEMTs with x = 0.7 in the channel have been built and evaluated across the -50°C to +200°C temperature range. These devices achieved room temperature drain current as high as 46 mA/mm and were absent of gate leakage until the gate diode forward bias turn-on at ~2.8 V, with a modest -2.2 V threshold voltage. A very large Ion/Ioff current ratio, of 8 × 109 was demonstrated. A near ideal subthreshold slope that is just 35% higher than the theoretical limit across the temperature range was characterized. The ohmic contact characteristics were rectifying from -50°C to +50°C and became nearly linear at temperatures above 100°C. An activation energy of 0.55 eV dictates the temperature dependence of off-state leakage.},
doi = {10.1149/2.0231712jss},
journal = {ECS Journal of Solid State Science and Technology},
number = 12,
volume = 6,
place = {United States},
year = 2017,
month =
}

Journal Article:
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  • We report on the growth of an In{sub 0.30}Ga{sub 0.70}As channel high-electron mobility transistor (HEMT) on a 200 mm silicon wafer by metal organic vapor phase epitaxy. By using a 3 μm thick buffer comprising a Ge layer, a GaAs layer and an InAlAs compositionally graded strain relaxing buffer, we achieve threading dislocation density of (1.0 ± 0.3) × 10{sup 7} cm{sup −2} with a surface roughness of 10 nm RMS. No phase separation was observed during the InAlAs compositionally graded buffer layer growth. 1.4 μm long channel length transistors are fabricated from the wafer with I{sub DS} of 70more » μA/μm and g{sub m} of above 60 μS/μm, demonstrating the high quality of the grown materials.« less
  • Two-dimensional current collapse imaging of a Schottky gate AlGaN/GaN high electron mobility transistor device was achieved by optical electric field-induced second-harmonic generation (EFISHG) measurements. EFISHG measurements can detect the electric field produced by carriers trapped in the on-state of the device, which leads to current collapse. Immediately after (e.g., 1, 100, or 800 μs) the completion of drain-stress voltage (200 V) in the off-state, the second-harmonic (SH) signals appeared within 2 μm from the gate edge on the drain electrode. The SH signal intensity became weak with time, which suggests that the trapped carriers are emitted from the trap sites. The SH signalmore » location supports the well-known virtual gate model for current collapse.« less
  • An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al 0.85Ga 0.15N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high I on/I off current ratio greater than 10 7 and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. In conclusion,more » the room temperature voltage-dependent 3-terminal off-state drain current was adequately modeled with Frenkel-Poole emission.« less
  • An AlN barrier high electron mobility transistor (HEMT) based on the AlN/Al{sub 0.85}Ga{sub 0.15}N heterostructure was grown, fabricated, and electrically characterized, thereby extending the range of Al composition and bandgap for AlGaN channel HEMTs. An etch and regrowth procedure was implemented for source and drain contact formation. A breakdown voltage of 810 V was achieved without a gate insulator or field plate. Excellent gate leakage characteristics enabled a high I{sub on}/I{sub off} current ratio greater than 10{sup 7} and an excellent subthreshold slope of 75 mV/decade. A large Schottky barrier height of 1.74 eV contributed to these results. The room temperature voltage-dependent 3-terminalmore » off-state drain current was adequately modeled with Frenkel-Poole emission.« less
  • The influence of construction of the buffer layer and misorientation of the substrate on the electrical properties of In{sup 0.70}Al{sup 0.30}As/In{sup 0.76}Ga{sup 0.24}As/In{sup 0.70}Al{sup 0.30}As quantum wells on a GaAs substrate is studied. The temperature dependences (in the temperature range of 4.2 K < T < 300 K) and field dependences (in magnetic fields as high as 6 T) of the sample resistances are measured. Anisotropy of the resistances in different crystallographic directions is detected; this anisotropy depends on the substrate orientation and construction of the metamorphic buffer layer. In addition, the Hall effect and the Shubnikov–de Haas effect aremore » studied. The Shubnikov–de Haas effect is used to determine the mobilities of electrons separately in several occupied dimensionally quantized subbands in different crystallographic directions. The calculated anisotropy of mobilities is in agreement with experimental data on the anisotropy of the resistances.« less