Monolithic photovoltaic IV-VI-on-Si infrared sensor array with integrated readout electronics

A fully monolithic infrared sensor array fabricated in a narrow-gap semiconductor (NGS) layer grown epitaxially on an active Si substrate is realized for the first time. The array is arranged bilinearly 2*128 with the readout circuits located at both sides. The photovoltaic IR sensors are delineated in a narrow-gap lead-chalcogenide (IV-VI) layer of only about 2- mu m thickness. Epitaxy is achieved with an intermediate CaF/sub 2//BaF/sub 2/ buffer for compatibility reasons. Compared to other approaches, like silicides or quantum-well detectors, photovoltaic sensors fabricated in a NGS exhibit high quantum efficiencies (>50%). and much higher operating temperatures at a given noise level are possible. Low-cost monolithic NGS-Si infrared focal plane arrays with cutoff wavelengths both for the 3-5- mu m and the 8-12- mu m range are possible.