The use of multiple internal reflection on extrinsic silicon infrared detection

The sensitivity of a silicon extrinsic infrared detector is enhanced by increasing the absorption path by multiple internal reflection utilizing V-grooves on a [100]-oriented silicon wafer for light coupling. Planar detectors were fabricated with gold-doped silicon as a prototype study, in which the spectral response, the influences of temperature, and the photoconductive detector quantum efficiency were characterized. The result indicates that the peak of the photoconductive spectrum is located at 0.9 eV, which is equal to 1.67 times the threshold for extrinsic photoconduction, as generally expected from the theoretical calculations.