High-Temperature Stability of Copper-Gate AlGaN/GaN High Electron Mobility Transistors

Jin-Ping AO  Daigo KIKUTA  Naotaka KUBOTA  Yoshiki NAOI  Yasuo OHNO  

IEICE TRANSACTIONS on Electronics   Vol.E86-C   No.10   pp.2051-2057
Publication Date: 2003/10/01
Online ISSN: 
Print ISSN: 0916-8516
Type of Manuscript: Special Section PAPER (Special Issue on Heterostructure Microelectronics with TWHM2003)
Cu-gate,  AlGaN/GaN,  high electron mobility transistor,  gate leakage current,  high-temperature stability,  

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High-temperature stability of copper (Cu) gate AlGaN/GaN high electron mobility transistors (HEMTs) was investigated. Samples were annealed at various temperatures to monitor the changes on device performances. Current-voltage performance such as drain-source current, transconductance, threshold voltage and gate leakage current has no obvious degradation up to annealing temperature of 500 and time of 5 minutes. Also up to this temperature, no copper diffusion was found at the Cu and AlGaN interface by secondary ion mass spectrometry determination. At annealing temperature of 700 and time of 5 minutes, device performance was found to have degraded. Gate voltage swing increased and threshold voltage shifted due to Cu diffusion into AlGaN. These results indicate that the Schottky contact and device performance of Cu-gate AlGaN/GaN HEMT is stable up to annealing temperature of 500. Cu is a promising candidate as gate metallization for high-performance power AlGaN/GaN HEMTs.