Geiger-mode operation of ultraviolet avalanche photodiodes grown on sapphire and free-standing GaN substrates

E. Cicek*, Z. Vashaei, R. McClintock, C. Bayram, M. Razeghi

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

51 Scopus citations

Abstract

GaN avalanche photodiodes (APDs) were grown on both conventional sapphire and low dislocation density free-standing (FS) c-plane GaN substrates. Leakage current, gain, and single photon detection efficiency (SPDE) of these APDs were compared. At a reverse-bias of 70 V, APDs grown on sapphire substrates exhibited a dark current density of 2.7× 10-4 A/ cm2 whereas APDs grown on FS-GaN substrates had a significantly lower dark current density of 2.1× 10-6 A/ cm2. Under linear-mode operation, APDs grown on FS-GaN achieved avalanche gain as high as 14 000. Geiger-mode operation conditions were studied for enhanced SPDE. Under front-illumination the 625-μ m2 -area APD yielded a SPDE of ∼13% when grown on sapphire substrates compared to more than 24% when grown on FS-GaN. The SPDE of the same APD on sapphire substrate increased to ∼30% under back-illumination-the FS-GaN APDs were only tested under front illumination due to the thick absorbing GaN substrate.

Original languageEnglish (US)
Article number261107
JournalApplied Physics Letters
Volume96
Issue number26
DOIs
StatePublished - Jun 28 2010

ASJC Scopus subject areas

  • Physics and Astronomy (miscellaneous)

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