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Proceedings Paper

Optimization of TCR and heat transport in group-IV multiple-quantum-well microbolometers
Author(s): Matthew Morea; Kevin Gu; Victoria Savikhin; Colleen S. Fenrich; Eric Pop; James S. Harris
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Paper Abstract

Group-IV semiconductors have the opportunity to have an equivalent or better temperature coefficient of resistance (TCR) than other microbolometer thermistor materials. By using multiple-quantum-well (MQW) structures, their TCR values can be optimized due to a confinement of carriers. Through two approaches – an activation energy approximation and a custom Monte Carlo transfer matrix method – we simulated this effect for a combination of Group-IV semiconductors and their alloys (e.g., SiGe and GeSn) to find the highest possible TCR, while keeping in mind the critical thicknesses of such layers in a MQW epitaxial stack. We calculated the TCR for a critical-thickness-limited Ge0.8Sn0.2/Ge MQW device to be about -1.9 %/K. Although this TCR is lower than similar SiGe/Si MQW thermistors, GeSn offers possible advantages in terms of fabricating suspended devices with its interesting etch-stop properties shown in previous literature. Furthermore, using finite element modeling of heat transport, we looked at another key bolometer parameter: the thermal time constant. The dimensions of a suspended Ge microbolometer’s supporting legs were fine-tuned for a target response time of 5 ms, incorporating estimations for the size effects of the nanowire-like legs on thermal conductivity.

Paper Details

Date Published: 19 September 2016
PDF: 7 pages
Proc. SPIE 9974, Infrared Sensors, Devices, and Applications VI, 99740M (19 September 2016); doi: 10.1117/12.2236166
Show Author Affiliations
Matthew Morea, Stanford Univ. (United States)
Kevin Gu, Stanford Univ. (United States)
Victoria Savikhin, Stanford Univ. (United States)
SLAC National Accelerator Lab. (United States)
Colleen S. Fenrich, Stanford Univ. (United States)
Eric Pop, Stanford Univ. (United States)
James S. Harris, Stanford Univ. (United States)

Published in SPIE Proceedings Vol. 9974:
Infrared Sensors, Devices, and Applications VI
Paul D. LeVan; Ashok K. Sood; Priyalal Wijewarnasuriya; Arvind I. D'Souza, Editor(s)

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