AIGaAs/GaAs/AIGaAs DHBT's for HighTemperature Stable Circuits

High-temperature devices are required for a large number of industrial applications. In order to demonstrate the feasibility of a high temperature operating circuit on GaAs an operational amplifier was designed and fabricated.

A corresponding technology for transistors and circuits for operation up to 300°C with AlGaAs/GaAs/AlGaAs DHBT's is presented. For the amplifier circuit an open loop gain of 49.5 dB at room temperature and 35.8 dB at 200°C was measured, which is in good agreement with the circuit simulation. Hightemperature stability has been proven by a storage test at 400°C over 1000 h for the ohmic contact metallization and 200 h for the transistors.