A new monolithic approach for mid-IR focal plane arrays

Xie, C., Pusino, V. , Khalid, A. , Aziz, M., Steer, M. J. and Cumming, D. R.S. (2016) A new monolithic approach for mid-IR focal plane arrays. Proceedings of the SPIE: The International Society for Optical Engineering, 9987, 99870T. (doi: 10.1117/12.2241323)

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Antimonide-based photodetectors have recently been grown on a GaAs substrate by molecular beam epitaxy (MBE) and reported to have comparable performance to the devices grown on more expensive InSb and GaSb substrates. We demonstrated that GaAs, in addition to providing a cost saving substrate for antimonide-based semiconductor growth, can be used as a functional material to fabricate transistors and realize addressing circuits for the heterogeneously grown photodetectors. Based on co-integration of a GaAs MESFET with an InSb photodiode, we recently reported the first demonstration of a switchable and mid-IR sensible photo-pixel on a GaAs substrate that is suitable for large-scale integration into a focal plane array. In this work we report on the fabrication steps that we had to develop to deliver the integrated photo-pixel. Various highly controllable etch processes, both wet and dry etch based, were established for distinct material layers. Moreover, in order to avoid thermally-induced damage to the InSb detectors, a low temperature annealed Ohmic contact was used, and the processing temperature never exceeded 180 °C. Furthermore, since there is a considerable etch step (> 6 μm) that metal must straddle in order to interconnect the fabricated devices, we developed an intermediate step using polyimide to provide a smoothing section between the lower MESFET and upper photodiode regions of the device. This heterogeneous technology creates great potential to realize a new type of monolithic focal plane array of addressable pixels for imaging in the medium wavelength infrared range without the need for flip-chip bonding to a CMOS readout chip.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Xie, Mr Chengzhi and Cumming, Professor David and Pusino, Mr Vincenzo and Khalid, Dr Ata-Ul-Habib and Aziz, Dr Mohsin and Steer, Dr Matthew
Authors: Xie, C., Pusino, V., Khalid, A., Aziz, M., Steer, M. J., and Cumming, D. R.S.
College/School:College of Science and Engineering > School of Engineering > Electronics and Nanoscale Engineering
Journal Name:Proceedings of the SPIE: The International Society for Optical Engineering
Publisher:Society of Photo-optical Instrumentation Engineers
ISSN (Online):1996-756X
Published Online:26 September 2016
Copyright Holders:Copyright © 2016 SPIE
First Published:First published in Proceedings of the SPIE: The International Society for Optical Engineering 9987: 99870T
Publisher Policy:Reproduced in accordance with the publisher copyright policy

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