EHF Heterojunction Bipolar Transistors
Technical rept. 1 Nov 1988-31 Dec 1989
TEXAS INSTRUMENTS INC DALLAS
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The purpose of this work is to determine if strained layers can be used to enhance performance for GaAs-based HBTs Tasks 4 and 5, we have investigated the use of InGaAs layers in the base and emitter cap layer. The purpose is to aid in formation of ohmic contacts and, in the case of InGaAs in the base region, also to serve as an etch stop. The performance of this device is comparable to that of a GaAsAlGaAs control device with no InGaAs layers, so we conclude that the use of InGaAs contact layers does not significantly improve performance. However, the use of an InGaAs etch-stop layer in the base greatly simplifies device processing, which will enable us to use thinner base regions with reduced transit times and, therefore, will improve device frequency response.
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