Pressure sensors based on AlGaAs doped with Te and Sn

Abstract

Resistivity and Hall concentration in AlGaAs layers have been measured as a function of pressure up to 25 kbar and of temperature from 77 K to 400 K. The layers were grown by LPE on GaAs and doped with Te and Sn. We first studied the properties of Al_xGal_1-x As with Al composition x from 0.1 to 0.3. Then we measured the graded-gap layers with x varying e.g., from 10% to 40%. Such graded-gap layers can be considered as the parallel connection of layers with uniform composition. They reveal strong pressure sensitivity and flat temperature variation of resistance. Tin-doped layers are good candidates for “laboratory” pressure sensors operating up to 30 kbar in the 77-300 K temperature range. Tellurium-doped layers reveal metastable properties below 120K but they can be useful for pressure sensing in the high-temperature range. The properties of graded-gap AlGaAs layers are superior to those of manganin and InSb sensors.

Key Words:

• Pressure sensors
• AlGaAs
• graded-gap