Degradation Mechanism of AlGaAs/InGaAs Power Pseudomorphic High-Electron-Mobility Transistors under Large-Signal Operation

概要

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We have comprehensively investigated the degradation mechanism of output power in AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors (PHEMTs) under large-signal operation. The degradation of output power is caused by the decrease in maximum drain current ($I_{\text{max}}$) around the knee voltage ($V_{\text{k}}$) with an increase in drain resistance ($R_{\text{d}}$). The decrease in $I_{\text{max}}$ originates from a degradation layer containing a significant amount of oxygen formed at the drain recess surface region. This layer causes a reduced carrier density in the drain region underneath, resulting in a decreased $I_{\text{max}}$ and an increased $R_{\text{d}}$. The decrease in $I_{\text{max}}$ is accelerated with increasing drain voltage, temperature, and humidity. These results suggest that the degradation of output power in the PHEMTs is mainly determined by the growth of a corrosion layer owing to an electrochemical reaction between O2 and/or H2O and the semiconductor surface. We successfully suppress the output power degradation due to this electrochemical corrosion reaction with the help of a special surface treatment prior to the deposition of a passivation film on the recess surface. We demonstrate a highly reliable RF operation of PHEMTs in air even without a hermetic package.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2008-02-25