Evaluation of A1xGa1xAs for HighTemperature Electronic Junction Device Applications

Mes-isolated, p⁺nn⁺, GaAs/AlxGa1-xAs/GaAs (0.10<x<0.5), double-heterojunction diodes are examined over the full temperature range from 50 to 400°C. AlxGa1-xAs is selectively used to suppress reverse junction leakage. GaAs is used for heterojunction contacts and as an encapsulant for the chemically reactive AlxGa1-xAs. An AlAs concentration of approximately 30% was found to provide significant improvements in the high-temperature reverse junction leakage (compared to GaAs homojunctions) without the necessity of going to higher values of x, Extending the diode work to three-terminal devices, a heterojunction- collector bipolar junction transistor was fabricated. These results demonstrate that AlxGa1-xAs coupled with GaAs for contacting and encapsulation is a good materials system for high-temperature junction device applications.