Semiconductor pressure sensor - using change in electrical resistance of multilayer structure of gallium arsenide-phosphide

摘要

Semiconductor pressure sensor, using a body based on a solid soln. AB1-xCx, made of two semiconductors AB, AC, the first having a direct band gap, the second an indirect band gap, Both with an energy min. A device, e.g. an ohmmeter, measures the alteration in resistance due to change in pressure. The body (1) uses two gps. of alternate layers (2,3) with different values of x, where the changes in x and the vol. ratio 2:3 are used to compensate for loss of sensitivity due to temp. change. The loss of sensitivity in layer (2) in one gp. is compensated by increased sensitivity in layer (3) in the other gp. Body (1) is pref. GaAs1-xPx; where x = 0.2-0.4, and the difference between the max. and min. values of x = 0.02-0.2. Layers (2,3) are pref. each 200-3000 angstroms thick, and contain 2-7 x 1018/cm.3 of a dopant with low energy level. Device measures e.g. the pressure in oil drilling; pipes; hydraulic or pneumatic systems in aircraft; or in IC engines.