PRESSURE SENSOR USING POLYCRYSTALLINE GERMANIUM FILMS PREPARED BY PLASMA-ASSISTED CHEMICAL VAPOR-DEPOSITION

Pressure sensors in the form of polycrystalline semiconducting films on a stainless steel diaphragm covered with an insulating layer have been fabricated. Phosphorus-doped polycrystalline germanium films are prepared by plasma-assisted chemical vapour deposition (plasma-CVD) and used as the sensing part of these devices. The deposition temperature is between 200 and 400 °C and the PH3/GeH4 ratio is ∼3.6 × 10-2. The gauge factor of these films is larger than 30, and is more than twice that of polycrystalline silicon films prepared at 800 °C. The sensitivity of the pressure sensor is more than 1.5 times higher than that of devices using polycrystalline silicon thin films. © 1990.