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 device breakdown in the off-state in L(G) =0.28 mu m gate-length pseudomorphic InALAs/InxGa1-xAs(0.53<x<0.7) High Electron Mobility Transistors on InP substrate is presented. The study identifies the present limitations of this type of device made with this material system. The investigation encompasses temperature and mole fractional dependent two-terminal and three-terminal de-measurements. The results of the investigation clarify that breakdown is a combined process of thermionic field emission and impact ionization. Up to high drain bias, thermionic field emission is the dominant process, only at very high drain bias impact ionization occurs. The experimental results also indicate that off-state breakdown is surface related. The drain-source breakdown voltages were determined to be V/(BRDS) =8 V, 5.9 V, 5.2 V, 4.3 V, 2.5 V for x=0.53, 0.59, 0.62, 0.65 and x=0.7, respectively. The two-terminal gate-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.