The Seebeck effect in highly conductive mu c-Ge:H films and its application to sensors

By combining a plasma CVD (chemical vapor deposition) system with a real-time annealing monitoring system, a highly conductive mu c-Ge:H film has been successfully fabricated on a glass substrate. This film generates a large amount of thermoelectric power (maximum -420 mu V/K). Using this microcrystalline Ge:H film thermopile, an optical power sensor and thermal vacuum gauge have been developed. In particular, when this mu c-Ge:H thermopile was used together with a low-reflectance Ni-P optical absorber, a high-accuracy, quick-response laser beam power sensor with the following characteristics was realized: responsivity, 0.3 mV/mW; response time, 1.8 s; wavelength range, 0.4 to 1.8 mu m; diameter of active area, 6 mm phi ; and resistance, 600 Omega to 1 k Omega . >