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Bolometers on macroporous silicon

Oleg Lytvynenko 

Institute of Semiconductor Physics (ISP), Nauki pr., Kyiv 03028, Ukraine

Abstract

Multi-element IR-detectors of a new type - uncooled bolometric, pyroelectric and thermoelectric matrices have been actively developed during recent years. The important characteristics required of microbolometric matrices are a high temperature coefficient of electrical resistance, low excess noise and good radiation absorption in the working spectral region. The structures based on amorphous or polycrystalline silicon satisfy such requirements. In this work the results of research into macroporous silicon structures made by photoanodic etching are given. The two-dimensional photonic structures on the basis of the macroporous silicon are perspective due to capability of a electromagnetic spectrum transformation by macropores. The light-assisted method of electrochemical etching of n-Si allows the formation of cylindrical macropores with a high ratio of pore depth to pore diameter and with strong periodicity. Such structures are highly promising for modification of the electromagnetic wave spectra in semiconductor devices. Anomalous coefficients of light absorption allow the development of thermal- and photo-sensors on the basis of macroporous silicon.
In this work ohmic structures of the type In-n-Si and In-macroporous n-Si were formed by thermal evaporation of indium in an atmosphere of hydrogen. The bolometric characteristics of macroporous silicon were estimated. The temperature coefficient of resistance ranges from 0.4 - 1% at room temperature to 1.5 - 4% at 77K. Noise level is (2x5)10-9 VHz-1/2 for frequencies > 10 Hz, and the detectivity of thermal bolometric elements on the base of macroporous silicon might be equaled 5x109 cmHz1/2W-1. So the investigated macroporous silicon structures are promising for multi-element thermal sensor fabrication due to a high temperature resistance coefficient, low excess noise and good radiation absorption in the working spectral region.

 

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Presentation: poster at E-MRS Fall Meeting 2004, Symposium D, by Oleg Lytvynenko
See On-line Journal of E-MRS Fall Meeting 2004

Submitted: 2004-03-09 13:53
Revised:   2009-06-08 12:55