(Invited) Displacement Damage and Single Event Effects in AlGaN/GaN HEMTs

• Published in: Meeting abstracts (Electrochemical Society) Vol. MA2016-02; no. 31; p. 2051
• Main Authors: Koehler, Andrew D., Anderson, Travis J, Khachatrian, Ani, Roche, Nicolas J.-H., Buchner, Stephen, Weaver, Brad D, Hobart, Karl D, Kub, Francis J
• Format: Journal Article
• Language: English
• Published: 01.09.2016
• ISSN: 2151-2043; 2151-2035
• DOI: 10.1149/MA2016-02/31/2051

Superior advantages of AlGaN/GaN high electron mobility transistors (HEMTs) from a size, weight, and power perspective make this technology desirable for use in outer space applications. However, the harsh environment in space includes bombardment of various types of radiation, which can degrade the performance and reliability of these devices. Displacement damage refers to atomic displacement within the semiconductor crystal lattice. This is permanent damage that permanently impacts the device characteristics. High-energy (2 meV) protons at various fluences, up to 6 x 10 14 H + /cm 2 were used to investigate the impact of displacement damage on AlGaN/GaN HEMTs. A reduction in the maximum drain current is observed, which is also attributed to a decrease in the two-dimensional electron gas (2DEG) mobility and sheet carrier density. A roughened interface between the AlGaN and GaN layers from atomic recoiling during irradiation has been identified as the mechanism for this mobility decrease. We have attributed the change in sheet carrier density to radiation-induced recombination centers created within the GaN. This results in a decrease in the Fermi level of the GaN, which also decreases the number of mobile electrons in 2DEG. Single event transients generated from energetic particles passing through the device create electrons and holes, which are collected at the terminals, are a potential reliability issue for the GaN HEMTs. A nondestructive focused pulsed-laser technique is used to investigate single event effects in the GaN HEMT devices, both before and after proton irradiation. Characteristics such as the peak amplitude, width, and total charge collected are investigated at various bias conditions and at different locations in the GaN HEMTs. The maximum charge collected is identified to be at the location corresponding to the peak electric field within the device. Defects within the GaN HEMTs induced by proton irradiation increase the time constant of the single event decay. Three distinct trapping time constants have been identified from extracted curve fits to the single event decay transient.