Bulletin of the American Physical Society
APS March Meeting 2010
Volume 55, Number 2
Monday–Friday, March 15–19, 2010; Portland, Oregon
Session K1: Poster Session II (2:00 pm - 5:00 pm)
Tuesday, March 16, 2010
Room: Exhibit CD
Abstract ID: BAPS.2010.MAR.K1.8
Abstract: K1.00008 : Defect-related recombination and free-carrier diffusion near an isolated defect in GaAs*
Preview Abstract Abstract
When defects are present in semiconductors, localized energy levels appear within the bandgap. These new electronic states accommodate heat-generating recombination -- a problematic energy loss mechanism in many semiconductor devices. But at high excitation, the density of electrons and holes is higher, so they encounter each other more frequently. Early encounters augment light-emitting recombination, reducing the average lifetime and diffusion distance so the carriers are less likely to reach defects. In images of the light emitted by GaAs, we observe isolated dark regions (defects) where the darkened area decreases substantially with increasing excitation. When we modeled the behavior with a simulation that allows for lifetime-limited diffusion and defect-related recombination only through mid-bandgap energy levels, we did not obtain good agreement between the experimental and simulated images. We are now testing a more sophisticated model which allows for an arbitrary distribution of defect levels within the bandgap.
*We thank Jeff Carapella for growing the test structures, and Caroline Vaughan and Adam Topaz for their work on finding the DOS functions. We also thank the Davidson Research Initiative and the Donors of the ACS - Petroleum Research Fund.
To cite this abstract, use the following reference: http://meetings.aps.org/link/BAPS.2010.MAR.K1.8
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