PHOTOEMISSION SPECTROSCOPY OF AL0.27GA0.73AS-AS PHOTODIODES

We report on photoemission measurements of MBE-grown Al0.27Ga0.73As p- i-n structures in which the optically active insulating layers contain arsenic precipitates (Al0.27Ga0.73As:As). Al0.27Ga0.73As:As layers we re formed by low temperature growth of Al0.27Ga0.73As followed by a hi gh temperature anneal. GaAs layers grown in this way have been reporte d to be sensitive to subband-gap light. A Fowler plot constructed from an internal photoemission measurement gave a barrier height of 0.93 e V. We compare this result with the barrier height of arsenic in GaAs t hat was found to be 0.7 eV using the same structure and measurement sc heme. This result demonstrates that the barrier height of embedded met allic arsenic clusters in AlxGa1-xAs is consistent with the heterostru cture conduction band offset and can be selected by changing the compo sition of the host material.