Observation of optically detected magnetic resonance signals in AlxGa1−xAs

Abstract

Optically detected magnetic resonance (ODMR) techniques which utilize weak spin effects on deep photoluminescence have been applied to MBE AlxGa1−xAs. ODMR [unlike conventional electron paramagnetic resonance (EPR)] experiments is ideally suited for thin epitaxial samples. Using this technique we have obtained results on molecular-beam epitaxy (MBE) AlxGa1−xAs grown at substrate temperatures of 570 and 620 °C. The four-line ODMR spectrum observed from AlxGa1−xAs at low x values is attributed to Ga atoms not on their normal sites. The physical defect we have ascribed to this signal is a Ga interstitial. To our knowledge this is the first observation of a self-interstitial in the GaAs–AlxGa1−xAs system. We suggest that the level ME6 observed in deep-level transient spectroscopy (DLTS) experiments on MBE grown under similar conditions is the Ga interstitial observed in the ODMR experiment. For x>0.3 the Ga spectrum is still observed but an additional single unsplit magnetic resonance line appears which might be due to oxygen.