Degradation mechanisms of GaAs PHEMTs in high humidity conditions

Abstract

We have studied the degradation mechanism of Al- GaAdInGaAs pseudomorphic HEMTs (FHEMTs) under high humidity conditions. The degraded samples under high humidity condition show a decrease in maximum drain current (Imax) and positive shift in threshold voltage (Vth). It was found that the Vth shift depends on gate orientation, which indicates that Vth shft is caused by piezoelectric effect due to stress change near the gate. Cross-sectional transmission electron microscopy (TEM) images from the deteriorated devices reveal the existence of a damaged tecess surface region and a peeling of passivation film. At the interface between passivation fh and AlGaAs surface, diffusion of Ga, As and AI into passivation film was observed by secondary ion mass spectrometry (SIMS). From these results, degradation of PHEMT has mainly two mechanisms: positive shift in Vth due to stress change under the gate which might be caused by the peeling of passsivation, and a decrease in Imax due to surface degradation at AlGaAs recess regions caused by diffusion phenomena of Ga,As and AI. The pre-deposition treatment effectively suppresses the degradation of pHEMTs under high humidity without degradation of high frequency performances.

Hot-Carrier-Related Increase in Drain Resistance and Its Suppression by Reducing Contaminants in InP-Based HEMTs

“…This breakage was probably caused by excess etching of the edge of the semiconductor during the BT test by remnant chemicals because of insufficient cleaning after the recess etching process. This excess etching is an electrochemical reaction, whose mechanism is similar to oxygenrelated degradation of pseudomorphic HEMTs (PHEMTS) in a humid environment [23]. In that report, the interaction of hot holes with oxide induced device degradation.…”

“…Lot 2 devices from three different wafers had the same dependence of stress bias as lot 3 devices. fixed charges derived from contaminants or defects introduced at fabrication, which is similar to the hot carrier degradation mechanism of PHEMTs [23].…”

The Design and Life Test of a Multifunction Power Amplifier for Space Application

“…With respect to humidity and hydrogen related degradation, the main signatures are the reduction of drain current, Freq (GHz) Figure 10: The insertion loss and isolation against frequency before (blue color traces) and after (red color traces) temperature stress. which leads to the reduction of output power, especially when the DUT is stressed with high temperature condition combined with humidity and hydrogen effects [25,26]. The possibility of humidity and hydrogen within the hermetic package could cause the adhesion phenomenon with respect to the passivation layer and the damage of the surface state of the semiconductor layer.…”

Characteristics Modeling of GaN Class-AB Dual-Band PA Under Different Temperature and Humidity Conditions

“…It is mainly due to the above reasons; the PA's performance degradation for the changes in temperature and humidity conditions is a hot topic of research [40]- [48]. However, most of the published papers are focused on the PA's performances degradations limited to the individual characteristic temperature and humidity, for instance, 85℃/85%RH [40], 121℃/100%RH [40], 0℃ [41], 25℃ [42], 50℃ [49], 80℃ [50], 100℃ [43], 130℃/60%RH [44], 130℃/40%RH [44].…”

“…It is mainly due to the above reasons; the PA's performance degradation for the changes in temperature and humidity conditions is a hot topic of research [40]- [48]. However, most of the published papers are focused on the PA's performances degradations limited to the individual characteristic temperature and humidity, for instance, 85℃/85%RH [40], 121℃/100%RH [40], 0℃ [41], 25℃ [42], 50℃ [49], 80℃ [50], 100℃ [43], 130℃/60%RH [44], 130℃/40%RH [44]. Measurement of a PA's temperature and humidity dependence at specific temperature/humidity points does not provide enough information to model the relationships of the PA's performance degradations in actual environmental conditions [34].…”