Pressure sensors based on AlGaAs doped with Te and Sn

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 stu died the properties of AlxGa1-xAs with Al composition x from 0.1 to 0.3. Th en 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 laye rs with uniform composition. They reveal strong pressure sensitivity and ha t temperature variation of resistance. Tin-doped layers are good candidates for "laboratory" pressure sensors operating up to 30kbar in the 77-300K te mperature range. Tellurium-doped layers reveal metastable properties below 120K but they can be useful for pressure sensing in the high-temperature ra nge. The properties of graded-gap AlGaAs layers are superior to those of ma nganin and InSb sensors.