BREAKDOWN MECHANISMS IN PSEUDOMORPHIC INALAS INXGA1-X HIGH-ELECTRON-MOBILITY TRANSISTORS ON INP .1. OFF-STATE/

A systematic experimental study on the mechanisms which are inducing d evice breakdown in the off-state in L(G) =0.28 mu m gate-length pseudo morphic InALAs/InxGa1-xAs(0.53<x<0.7) High Electron Mobility Transisto rs on InP substrate is presented. The study identifies the present lim itations of this type of device made with this material system. The in vestigation encompasses temperature and mole fractional dependent two- terminal and three-terminal de-measurements. The results of the invest igation clarify that breakdown is a combined process of thermionic fie ld emission and impact ionization. Up to high drain bias, thermionic f ield emission is the dominant process, only at very high drain bias im pact ionization occurs. The experimental results also indicate that of f-state breakdown is surface related. The drain-source breakdown volta ges were determined to be V/(BRDS) =8 V, 5.9 V, 5.2 V, 4.3 V, 2.5 V fo r x=0.53, 0.59, 0.62, 0.65 and x=0.7, respectively. The two-terminal g ate-drain breakdown voltages at room-temperature were determined to be V-BRGD=11.9 V, 11.3 V, 7.9 V, 7.2 V, 6.7 V for x=0.53, 0.59, 0.62, 0. 65 and x=0.7, respectively.