ELECTRICAL-TRANSPORT PROPERTIES OF SILICON DELTA-DOPED AL0.30GA0.70ASSAMPLES SHOWING SUPPRESSION OF THE DX CENTER FEATURES

Photoconductivity and photo-Hall density measurements using an infrare d light emitting diode as the light source were carried out on single silicon delta-doped Al0.30Ga0.70As samples as a function of temperatur e. The samples were grown by molecular beam epitaxy at 530 degrees C a nd 600 degrees C, We have studied the effect of etching the cap layer on the electrical transport properties. An observed persistent photoco nductivity effect is explained using a model of parallel conduction in two nearby spatially separated channels. We will present evidence tha t the DX center is not active for nearly ideal delta-doped samples. We have proposed that the DX-center level related to the conduction-band minimum is strongly dependent on the silicon delta-doping density and on the growth conditions. (C) 1997 American Vacuum Society.