HYDROSTATIC-PRESSURE SENSORS BASED ON SOLID-STATE TUNNELING DEVICES

A new type of a hydrostatic pressure sensing device based on a thin AlAs/GaAs/AlAs double-barrier resonant tunneling (DBRT) structure is reported, which operates at room temperature. The current swing (DELTAI) in the negative-differential resistance region depends linearly on the applied pressure (p). Diodes with an operating range of DELTAp = 6000 bar (12,000 bar) and a high sensitivity of 170 x 10(-3) kbar-1 (85 x 10(-3) kbar-1) are realized with an AlAs barrier layer thickness of 2.8 nm (2.3 nm). Pressure sensing at 300 K is enabled by an elastic electronic tunneling process through the GAMMA-DBRT conduction band profile in combination with a sensitive pressure-dependent inelastic tunneling process through the transversal X-valleys in the AlAs barriers. The applied pressure decreases the GaAs/AlAs GAMMA-X discontinuity and yields to a significant enhancement of the valley current. The pressure coefficient (DELTAI/DELTAp) and operating range (DELTAp) can be adjusted by a variation of the AlAs barrier thickness.