Regensburg 2004 – wissenschaftliches Programm
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HL: Halbleiterphysik
HL 43: III-V Halbleiter II
HL 43.5: Vortrag
Donnerstag, 11. März 2004, 16:15–16:30, H14
Optical cross sections of the deep defect centers in low temperature grown GaAs — •G.H. Döhler1, C. Steen1, C. Metzner1, R. Schmidt1, P. Kiesel2, and S. Malzer1 — 1Institut für Technische Physik I, FAU Erlangen-Nürnberg, Erlangen, Germany — 2Palo Alto Research Center Incorporated, Palo Alto, California
“Low Temperature Grown GaAs" (LT-GaAs) grown by molecular beam epitaxy (MBE) at low substrate temperatures (190 ∘C - 300 ∘C) contains a high concentration of (non-stoichiometric) excess As, which is incorporated as EL2-like point defects (AsGa) and As precipitates. At low temperatures, where the thermal emission rates are negligible, the occupation of the deep defects can be changed optically. A determination of the (wavelength-dependent) optical cross sections is possible if initial conditions can be adjusted where all defects are depleted or filled, respectively. We have determined the optical cross sections σn and σp of the defects in LT-GaAs. We have used a p-i-n structure with a thin, only a few nm thick, layer of LT-GaAs embedded in the i-region of a n-i-p diode. By applying a reverse bias we are able to control the charge in the LT-GaAs layer [1]. The charge of the LT-GaAs layer is directly correlated with the channel conductance Gnn of the (thin) top n-layer. The optical cross sections for both electrons and holes were deduced by determining the initial slope of the Gnn change when the illumination starts. The results were confirmed by the determination of the ratio of σn and σp deduced from the steady Gnn value under illumination.
[1] K.-F.-G. Pfeiffer et al., Appl. Phys. Lett. 77, 2349 (2000)