PHOTOTHERMAL WAVELENGTH MODULATED PHOTOCURRENT PHENOMENA IN SI DELTA-DOPED GAAS

The first observation of photothermal wavelength modulated photocurren t (PWMPC) phenomena in a MBE grown p-GaAs sample in which a single Si- layer was embedded with a delta-type profile, is reported. Two spectra l features were observed at 1.5137 eV and 1.5115 eV at 20 K. These pea ks were attributed to the (D-0, X) and (A(0), X)-excitons bound to neu tral donors and accepters respectively. We studied the temperature dep endence of these excitonic peak positions at temperatures between 20-9 0 K. Additionally, we demonstrate a blue shift of spectra under low le vel illumination intensity. PWMPC phenomena and the nature of the regi stered features were explored in detail. The dependence of the exciton ic peaks on the chopping frequency and the intensity is discussed. (C) 1998 Elsevier Science B.V. All rights reserved.