The effect of N-2 plasma damage on AlGaAs/InGaAs/GaAs high electron mobility transistors. I. DC characteristics

0.25 mum gate length AlGaAs/InGaAs/GaAs pseudomorphic high electron mobilit y transistors were exposed to inductively coupled plasma (ICP) N-2 discharg es at varied source power and rf chuck power. The plasma damage was charact erized by evaluating device extrinsic transconductance and saturated drain- source current, as well as Schottky gate ideality factor and reverse breakd own voltage as a function of both ICP source power and rf chuck power. Auge r and atomic force microscopy were also used to characterize the atomic rat io and roughness of plasma damaged surface, respectively. At a lower range of ICP source power (between 100 and 300 W) with a constant rf power of 10 W. the device performance was barely changed. But at higher ICP source powe r (greater than 400 W) and rf power (greater than 20 W), device characteris tics including gate ideality factor, reverse breakdown voltage and saturate d drain-source current were seriously degraded, in this plasma damage study , two device degradation mechanisms were identified. The first was ion bomb ardment induced lattice disorder that created generation-recombination cent ers and reduced the free carrier concentration. The second was preferential loss of As from GaAs surface and this also created deep level states, whic h gave rise to gate leakage current. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.