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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. Mon . "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 = {Mon Aug 08 00:00:00 EDT 2016},
month = {Mon Aug 08 00:00:00 EDT 2016}
}
  • Low defect AlN/GaN high electron mobility transistor (HEMT) structures, with very high values of electron mobility (>1800 cm{sup 2}/V s) and sheet charge density (>3x10{sup 13} cm{sup -2}), were grown by rf plasma-assisted molecular beam epitaxy (MBE) on sapphire and SiC, resulting in sheet resistivity values down to {approx}100 {omega}/{open_square} at room temperature. Fabricated 1.2 {mu}m gate devices showed excellent current-voltage characteristics, including a zero gate saturation current density of {approx}1.3 A/mm and a peak transconductance of {approx}260 mS/mm. Here, an all MBE growth of optimized AlN/GaN HEMT structures plus the results of thin-film characterizations and device measurements are presented.
  • A series of six ultrathin AlN/GaN heterostructures with varied AlN thicknesses from 1.5–6 nm have been grown by molecular beam epitaxy on free-standing hydride vapor phase epitaxy GaN substrates. High electron mobility transistors (HEMTs) were fabricated from the set in order to assess the impact of barrier thickness and homo-epitaxial growth on transistor performance. Room temperature Hall characteristics revealed mobility of 1700 cm{sup 2}/V s and sheet resistance of 130 Ω/□ for a 3 nm thick barrier, ranking amongst the lowest room-temperature sheet resistance values reported for a polarization-doped single heterostructure in the III-Nitride family. DC and small signal HEMT electrical characteristics frommore » submicron gate length HEMTs further elucidated the effect of the AlN barrier thickness on device performance.« 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.
  • We provide theoretical and simulation analysis of the small signal response of SiO{sub 2}/AlGaN/GaN metal insulator semiconductor (MIS) capacitors from depletion to spill over region, where the AlGaN/SiO{sub 2} interface is accumulated with free electrons. A lumped element model of the gate stack, including the response of traps at the III-N/dielectric interface, is proposed and represented in terms of equivalent parallel capacitance, C{sub p}, and conductance, G{sub p}. C{sub p} -voltage and G{sub p} -voltage dependences are modelled taking into account bias dependent AlGaN barrier dynamic resistance R{sub br} and the effective channel resistance. In particular, in the spill-over region,more » the drop of C{sub p} with the frequency increase can be explained even without taking into account the response of interface traps, solely by considering the intrinsic response of the gate stack (i.e., no trap effects) and the decrease of R{sub br} with the applied forward bias. Furthermore, we show the limitations of the conductance method for the evaluation of the density of interface traps, D{sub it}, from the G{sub p}/ω vs. angular frequency ω curves. A peak in G{sub p}/ω vs. ω occurs even without traps, merely due to the intrinsic frequency response of gate stack. Moreover, the amplitude of the G{sub p}/ω vs. ω peak saturates at high D{sub it}, which can lead to underestimation of D{sub it}. Understanding the complex interplay between the intrinsic gate stack response and the effect of interface traps is relevant for the development of normally on and normally off MIS high electron mobility transistors with stable threshold voltage.« less