Material, physics, device physics, and technology of high-power pseudomorphic AlGaAs/InGaAs high electron mobility transistors.

摘要

High power pseudomorphic AlGaAs/InGaAs high electron mobility transistors (PHEMT's) are investigated using 2-D device simulation, spatially-resolved electro-luminescence, light emission spectra analysis, temperature dependence of off-state breakdown voltage/on-state gate current, and low frequency noise to improve power and reliability performance. A two-dimensional device simulation was used to exploit the off/on state breakdown origins in power PHEMT's and to explore the physical mechanisms responsible for the light emission in both conditions. A correlation between the simulated results and light emission spectra highlights the breakdown origins in power PHEMT's. The temperature dependence of off-state breakdown voltage and on-state gate current ranging from 30{dollar}spcirc{dollar}K to 400{dollar}spcirc{dollar}K also highlights the breakdown mechanisms in PHEMT's.; PECVD (plasma-enhanced chemical vapor deposition) nitride passivated PHEMT's processed with different surface conditions and on epitaxial wafers from different vendors were fabricated to study the off-state breakdown walkout (i.e. breakdown voltage increase) and hot carrier reliability. It has been shown that the breakdown walkout of passivated high-power PHEMT's depends on the surface process conditions and to a lesser degree on the starting wafers. No noticeable recovery after annealing @ 240{dollar}spcirc{dollar}C for 400 hours indicates a permanent breakdown walkout. The results suggest an alternative to optimizing PHEMT's process for reliability and to improving breakdown voltage.; The typical hot-carrier-induced device degradation characteristics are often observed in devices with a less-than ideal double gate recess and material layer design. With additional drain engineering work to optimize device power performance, the hot carrier effects can be alleviated drastically. However, depending on the nitride deposition processes and nitride quality, Schottky diode degradation was also observed during the hot carrier stress.; Meanwhile, the gate current and drain current low frequency noise characteristics were also investigated. The anomalous bias dependence of gate current noise due to the impact ionization hole current shows a strong dependence of {dollar}rm Isb{lcub}G{rcub}/Isb{lcub}DS{rcub}{dollar} factor. The gate leakage current reduction leading to the off-state breakdown walkout exhibits a nearly ideal 1/f noise characteristic with an {dollar}rm Isb{lcub}G{rcub}sp2{dollar} dependence, suggesting a surface generation-recombination current from the interface of passivation layer/semiconductor. The results indicate that 1/f noise technique is an essential tool to identify the gate leakage current mechanism.