Mid-infrared silicon/germanium focal plane detector arrays

Hartmut Presting; Johannes Konle; Markus Hepp; Horst Kibbel; Klaus Thonke; Rolf Sauer; Wolfgang A. Cabanski; Milan Jaros

doi:10.1117/12.342804

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19 March 1999 Mid-infrared silicon/germanium focal plane detector arrays

Hartmut Presting, Johannes Konle, Markus Hepp, Horst Kibbel, Klaus Thonke, Rolf Sauer, Wolfgang A. Cabanski, Milan Jaros

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Proceedings Volume 3630, Silicon-based Optoelectronics; (1999) https://doi.org/10.1117/12.342804
Event: Optoelectronics '99 - Integrated Optoelectronic Devices, 1999, San Jose, CA, United States

Abstract

Highly p-doped silicon/silicon-germanium (Si/SiGe) quantum well (QW) structures have been grown by molecular beam epitaxy (MBE) on <100> Si substrates for mid-infrared (3(mu) - 5(mu) ; 8(mu) - 12(mu) ) detection. These detectors operate at 77 K and are based on hetero-internal photoemission (HIP) of holes from a highly p-doped SiGe quantum well into a undoped silicon layer. They are grown on weakly-doped (50(Omega) cm), double-sided polished Si substrate on which the highly p-doped Si_1-xGe_x wells (p⁺⁺ approximately 5 10²⁰cm^-3) are deposited. The Ge content, doping level and the well width determine the operating wavelength. The samples have been characterized by secondary ion mass spectroscopy (SIMS), X-ray diffraction, and absorption measurements. Single mesa detectors as well as large area focal plane arrays (FPA) with 256 X 256 pixels have been fabricated from these samples using standard Si integrated processing techniques. Dark- and photocurrents have been measured at 77 K and up to 225 K. Broad photoresponse curves with peak external quantum efficiencies up to 0.5% have been measured at 77 K and 4$u. Detectivities in excess of 2 10¹⁰ cm(root)Hz/W have been obtained. We demonstrate that by varying the well design of the SiGe HIP detectors by means of Ge-content, doping and Ge gradients in double and stacked multi-wells the photoresponse peak and the shape of the spectrum can be tuned over a wide wavelength range. The fabricated 256 X 256 Si/SiGe FPA array has a pixel size of 21 X 21(mu) ² and a pitch of 24(mu) . The mesa detectors diameters range from 1 mm down to 125(mu) . The epitaxial versatility and the compatibility of the Si/SiGe array fabrication compared to the existing silicide fabrication process demonstrates the advantages of the SiGe system in comparison over commercially used silicide detectors.

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Hartmut Presting, Johannes Konle, Markus Hepp, Horst Kibbel, Klaus Thonke, Rolf Sauer, Wolfgang A. Cabanski, and Milan Jaros "Mid-infrared silicon/germanium focal plane detector arrays", Proc. SPIE 3630, Silicon-based Optoelectronics, (19 March 1999); https://doi.org/10.1117/12.342804

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