Pressure sensor using polycrystalline germanium films prepared by plasma assisted chemical vapor deposition

Pressure sensors were fabricated using polycrystalline germanium films on a stainless steel diaphragm covered with an insulating layer. The polycrystalline germanium films, the sensing part of this device, were prepared by plasma-assisted chemical vapor deposition (plasma-CVD) at temperatures between 200°C and 500°C. The gauge factor of these films was about 20-60. The values were two times larger than those of polycrystalline silicon films prepared at 600°C. The sensitivity of the pressure sensor was twice that of devices using polycrystalline silicon thin films. The gauge factor and resistance of these films decreased with increasing temperature. The sensor showed high sensitivity and good linearity