skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture

Abstract

A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture is demonstrated that leverages ultra-thin epitaxial layers to suppress surface-related gate lag. Two high-density two-dimensional electron gas (2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the top 2DEG serves as a quasi-equipotential that screens potential fluctuations resulting from distributed surface and interface states. The bottom channel serves as the transistor's modulated channel. Dual-channel AlN/GaN heterostructures were grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. HEMTs fabricated with 300 nm long recessed gates demonstrated a gate lag ratio (GLR) of 0.88 with no degradation in drain current after bias stressed in subthreshold. These structures additionally achieved small signal metrics f{sub t}/f{sub max} of 27/46 GHz. These performance results are contrasted with the non-recessed gate dual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with f{sub t}/f{sub max} of 48/60 GHz.

Authors:
; ; ; ;  [1]
  1. Naval Research Laboratory, Electronics Science and Technology Division, Washington, DC 20375 (United States)
Publication Date:
OSTI Identifier:
22594315
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 109; Journal Issue: 6; Other Information: (c) 2016 U.S. Government; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ALUMINIUM NITRIDES; ELECTRON GAS; ELECTRON MOBILITY; GALLIUM NITRIDES; HYDRIDES; INTERFACES; LAYERS; METRICS; MOLECULAR BEAM EPITAXY; MOLECULAR BEAMS; SIGNALS; STRESSES; SUBSTRATES; SURFACES; TRANSISTORS; TWO-DIMENSIONAL CALCULATIONS; VAPOR PHASE EPITAXY; VAPORS

Citation Formats

Deen, David A., E-mail: david.deen@alumni.nd.edu, Storm, David F., Scott Katzer, D., Bass, R., and Meyer, David J.. Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture. United States: N. p., 2016. Web. doi:10.1063/1.4961009.
Deen, David A., E-mail: david.deen@alumni.nd.edu, Storm, David F., Scott Katzer, D., Bass, R., & Meyer, David J.. Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture. United States. doi:10.1063/1.4961009.
Deen, David A., E-mail: david.deen@alumni.nd.edu, Storm, David F., Scott Katzer, D., Bass, R., and Meyer, David J.. 2016. "Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture". United States. doi:10.1063/1.4961009.
@article{osti_22594315,
title = {Suppression of surface-originated gate lag by a dual-channel AlN/GaN high electron mobility transistor architecture},
author = {Deen, David A., E-mail: david.deen@alumni.nd.edu and Storm, David F. and Scott Katzer, D. and Bass, R. and Meyer, David J.},
abstractNote = {A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture is demonstrated that leverages ultra-thin epitaxial layers to suppress surface-related gate lag. Two high-density two-dimensional electron gas (2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the top 2DEG serves as a quasi-equipotential that screens potential fluctuations resulting from distributed surface and interface states. The bottom channel serves as the transistor's modulated channel. Dual-channel AlN/GaN heterostructures were grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. HEMTs fabricated with 300 nm long recessed gates demonstrated a gate lag ratio (GLR) of 0.88 with no degradation in drain current after bias stressed in subthreshold. These structures additionally achieved small signal metrics f{sub t}/f{sub max} of 27/46 GHz. These performance results are contrasted with the non-recessed gate dual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with f{sub t}/f{sub max} of 48/60 GHz.},
doi = {10.1063/1.4961009},
journal = {Applied Physics Letters},
number = 6,
volume = 109,
place = {United States},
year = 2016,
month = 8
}
  • Effective electron mobility {mu}{sub eff} in channels of metal-oxide-semiconductor transistors with a gate length L in the range of 3.8 to 0.34 {mu}m was measured; the transistors were formed on wafers of the silicon-oninsulator type. It was found that {mu}{sub eff} decreases as L is decreased. It is shown that this decrease can be accounted for by the effect of series resistances of the source and drain only if it is assumed that there is a rapid increase in these resistances as the gate voltage is decreased. This assumption is difficult to substantiate. A more realistic model is suggested; thismore » model accounts for the observed decrease in {mu}{sub eff} as L is decreased. The model implies that zones with a mobility lower than that in the middle part of the channel originate at the edges of the gate. An analysis shows that, in this case, the plot of the dependence of 1/{mu}{sub eff} on 1/L should be linear, which is exactly what is observed experimentally. The use of this plot makes it possible to determine both the electron mobility {mu}{sub 0} in the middle part of the channel and the quantity A that characterizes the zones with lowered mobility at the gate's edges.« less
  • The effective mobility of electrons {mu}* in the inversion n-type channel of a field-effect transistor increases appreciably (as a result of space-charge ion polarization of the gate oxide) from the typical values of {approx_equal}820 cm{sup 2} V{sup -1} s{sup -1} to the values of {approx_equal}2645 cm{sup 2} V{sup -1} s{sup -1}, which exceed the electron mobility in bulk silicon. After polarization, the sheet concentration of Na{sup +} ions at the SiO{sub 2}/Si interface exceeds 6 x 10{sup 13} cm{sup -2}. The ions are almost completely neutralized by electrons in the inversion channel. As temperature T is decreased in the rangemore » from 293 to 203 K, {mu}* increases according to the law {mu}* {proportional_to} T{sup -0.82}. Apparently, the observed dependence {mu}*(T) is caused by the combined scattering of electrons by roughness of the Si/SiO{sub 2} interface surface, phonons, and the interface states. Depolarization of the oxide reverts {mu}* to the initial value. Anomalously large values of {mu}* are assumed to be either a consequence of the origination of pronounced structural stresses in the surface Si layer due to the oxide polarization or a result of a phase reconstruction of the inversion-channel region due to hybridization of the wave functions of electrons localized at the Na{sup +} ions with the wave functions of electrons in the inversion channel.« less
  • Effective electron mobility {mu}{sub eff} in channels of metal-oxide-semiconductor transistors with a gate length L in the range of 3.8 to 0.34 {mu}m was measured; the transistors were formed on wafers of the silicon-oninsulator type. It was found that {mu}{sub eff} decreases as L is decreased. It is shown that this decrease can be accounted for by the effect of series resistances of the source and drain only if it is assumed that there is a rapid increase in these resistances as the gate voltage is decreased. This assumption is difficult to substantiate. A more realistic model is suggested; thismore » model accounts for the observed decrease in {mu}{sub eff} as L is decreased. The model implies that zones with a mobility lower than that in the middle part of the channel originate at the edges of the gate. An analysis shows that, in this case, the plot of the dependence of 1/{mu}{sub eff} on 1/L should be linear, which is exactly what is observed experimentally. The use of this plot makes it possible to determine both the electron mobility {mu}{sub 0} in the middle part of the channel and the quantity A that characterizes the zones with lowered mobility at the gate's edges.« less
  • We present the real-time x-ray irradiation response of charge and pH sensitive solution gate AlGaN/GaN high electron mobility transistors. The devices show stable and reproducible behavior under and following x-ray radiation, including a linear integrated response with dose into the muGy range. Titration measurements of devices in solution reveal that the linear pH response and sensitivity are not only retained under x-ray irradiation, but an irradiation response could also be measured. Since the devices are biocompatible, and can be simultaneously operated in aggressive fluids and under hard radiation, they are well-suited for both medical radiation dosimetry and biosensing applications.