Abstract
Monolithic structures, in which the photodetectors are combined with signal multiplexers without bump bonding technology, are beneficial in order to manufacture high resolution infrared focal plane arrays and reduce their production cost. The GeSi/Si heterojunction photodetector can be easily integrated monolithically on Si multiplexers and is one of the most promising infrared detectors for high resolution focal plane arrays detecting the infrared irnage in the 10-μm spectral band. We have fabricated GeSi/Si heterojunction photodetectors by MBE technology and evaluated their photoresponse and dark current, and investigated the feasibility of the GeSi/Si heterojunction infrared focal plane array. The quantum efficiency has a maximum value at a GeSi thickness of 20nm and the cutoff wavelength can be tailored by the composition of the GeSi film. It was confirmed that the cutoff wavelength can also be controlled by the impurity concentration in the GeSi film. The dark current exhibited an ideal thermionic emission characteristic in a wide temperature range. The performance obtained in the preliminary experiments indicates that the GeSi/Si heterojunction technology has sufficient capability in realizing focal plane arrays with full TV resolution for the 10-μm infrared spectral band.
