Pressure sensors based on silicon doped GaAs-AlAs superlattices

We show how GaAs-AlAs short period superlattices, in place of AlGaAs thin l ayers, improve the performances of n-type III-V semiconductors as pressure sensing material. Pressure induced electron capture on relaxed silicon dono r sites (so called DX center) is responsible for the high pressure coeffici ent of resistance (30% per kbar). In comparison to AlGaAs, band gap enginee ring is employed to optimize both pressure and temperature sensitivities of GaAs-AlAs pseudoalloys between 0 and 200 degrees C under pressures up to 2 000 bars. An electrical characterization is made by performing resistance a nd Hall effect measurements as functions of hydrostatic pressure and temper ature on two microstructures forming the monolithic transducer. The heteros tructures consist of (GaAs)(9)-(AlAs)(4) superlattices doped with silicon a t concentrations of 1.4 x 10(17) and 2 x 10(18) cm(-3), respectively. Accur ate pressure measurements (resolution less than 0.2 bar) are performed on t wo resistors patterned on these microstructures. Monolithic microsensors ca n be designed on such a stacked GaAs-AlAs two-resistor microstructure. (C) 2000 American Institute of Physics. [S0021-8979(00)01006-9].