Date of Award

3-2005

Document Type

Thesis

Degree Name

Master of Science

Department

Department of Engineering Physics

First Advisor

Michael A. Marciniak, PhD

Abstract

Semiconductor performance is often characterized in terms of the rate at which its carrier recombination processes occur. Carrier recombination, including radiative, and Shockley-Read-Hall and Auger (both nonradiative), occurs at ultra-fast times in the picosecond or femtosecond regimes. A device which can measure both spectral data and temporal phenomena at this speed is the streak camera. The capability to do time-resolved spectroscopy of wide band gap semiconductors using a streak camera has been established at AFIT for the first time. Time resolved photoluminescence (TRPL) from samples of gallium nitride were measured at temperatures of 5 K over spectral bands of 36.6 Å and temporal ranges of 45 to 1970 ps, both instrument-limited. TRPL features at 3552 Å and 3587 Å were studied giving decay lifetimes of 43.2 ± 1.6 ps and 16.8 ± 3.4 ps, respectively. Shockley-Read-Hall, Radiative and Auger coefficients were found but parameterized in terms of experimental efficiency, η, which was not measured. These values, determined using a least-squares-error fit of the carrier recombination rate equation to collected data, are -9.3 x 109 ± 4.9 x 108 s-1, 7.5 x 1017 η, ± 8.0 x 1016 η cm3 /s and 1.8 x 1025 η2 cm6/s, respectively, for the first peak and -2.5 x 1010 ± 5.2 x 109 s-1, 4.9 x 1019 η ± 2.0 x 1019 η cm3/s and -1.4x1028 η2 ± 8.6 x 1027 η2 cm6/s for the second peak. Since alignment of the streak camera has not yet been optimized, large but unquantified uncertainty in these results exists. Isolating vibrations and improving streak camera alignment should reduce the uncertainty and permit data collection temporally resolved at hundreds of femtoseconds.

AFIT Designator

AFIT-GAP-ENP-05-04

DTIC Accession Number

ADA434205

Download

Share

COinS