Regensburg 2007 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 46: Poster 2

HL 46.79: Poster

Donnerstag, 29. März 2007, 15:00–17:30, Poster A

Temperature variations during low-temperature growth of GaMnAs — •Kamil Olejnik, Vit Novak, Miroslav Cukr, and Jiri Oswald — Institute of Physics AS CR, Cukrovarnicka 10, 162 53 Prague, Czech Republic

Substrate temperature is known to be a critical parameter in the low-temperature MBE growth of ferromagnetic GaMnAs layers. We report on significant temperature changes of the GaAs substrate determined by band-gap spectroscopy technique during the growth of the GaMnAs film. Typically, an increase of 20 - 40 degrees is observed within the first 20 nm of the growing layer, depending mainly on the Mn doping level; at the same time no increase of the thermocouple temperature is detected. The effect is attributed to the free carrier and Mn-acceptor related absorption, both increasing along with the increasing Mn content. A mathematical model is formulated based on the heat balance between the thermal sources, radiative cooling and the heat capacity of the substrate. Within the proposed overheating mechanism the onset of the surface roughening during the growth can be ascribed to reaching a certain critical substrate temperature. (Grant Nr.202/04/1519)