Temperature Dependence of Hole Impact Ionization Coefficient in 4H-SiC Photodiodes

Abstract:

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Hole initiated multiplication characteristics of 4H-SiC Separate Absorption and Multiplication Avalanche Photodiodes (SAM-APDs) with a n- multiplication layer of 2.7 µm were obtained using 325nm excitation at temperatures ranging from 300 to 450K. The breakdown voltages increased by 200mV/K over the investigated temperature range, which indicates a positive temperature coefficient. Local ionization coefficients, including the extracted temperature dependencies, were derived in the form of the Chynoweth expression and were used to predict the hole multiplication characteristics at different temperatures. Good agreement was obtained between the measured and the modeled multiplication using these ionization coefficients. The impact ionization coefficients decreased with increasing temperature, corresponding to an increase in breakdown voltage. This result agrees well with the multiplication characteristics and can be attributed to phonon scattering enhanced carrier cooling which has suppressed the ionization process at high temperatures. Hence, a much higher electric field is required to achieve the same ionization rates.

Info:

Periodical:

Materials Science Forum (Volumes 615-617)

Edited by:

Amador Pérez-Tomás, Philippe Godignon, Miquel Vellvehí and Pierre Brosselard

Pages:

311-314

DOI:

10.4028/www.scientific.net/MSF.615-617.311

Citation:

W.S. Loh et al., "Temperature Dependence of Hole Impact Ionization Coefficient in 4H-SiC Photodiodes", Materials Science Forum, Vols. 615-617, pp. 311-314, 2009

Online since:

March 2009

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$35.00

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