Breakdown Mechanisms in Pseudomorphic InAlAs/In_xGa_1-xAs High Electron Mobility Transistors on InP. II: On-State

Abstract

A systematic experimental study on the mechanisms inducing device breakdown in the on-state in L G =0.28µm gate-length pseudomorphic InAlAs/In x Ga 1- x As (0.53< x <0.7) high electron mobility transistors (HEMTs) on InP substrate is presented. The study provides comprehensive physical explanation for the mechanisms which limit the breakdown voltage in the open channel condition. The intention of this paper is to provide a profound understanding on the breakdown physics in the on-state of this type of device. From temperature dependent measurements and the evolution of the impact ionization rate as a function of bias we found that in this type of device on-state breakdown is dominated by impact ionization. Thermionic field emission was recognized to be negligible compared to impact ionization. The on-state breakdown voltage drops drastically with increased InAs-mole fraction x . The experimental results also indicate that on-state breakdown occurs in the channel layer. The drain-source breakdown voltages determined at 1% I DSS where V DSbr (300 K)=6.8 V, 5.7 V, 4.5 V, 4.1 V, 3.5 V for x =0.53, 0.59, 0.62, 0.65 and x =0.7, respectively.