LUMINESCENCE AND DEEP-LEVEL CHARACTERISTICS OF GAAS SI WITH ATOMIC LAYER EPITAXY-GROWN PREDEPOSITION LAYERS/

A relatively simple scheme for the growth of high optical quality GaAs layers on Si substrates by metalorganic chemical vapor deposition (MO CVD) technique is reported. The process is analogous to the convention al two-step growth procedure where the initial thin nucleating layer g rowth is done by atomic layer epitaxy (ALE) technique, implemented int o the MOCVD reactor itself. The photoluminescence from the layer is in creased to about sixfold by replacing the normal predeposition growth by the proposed ALE growth technique, Magnitude of luminescence is com parable to that obtained from layers grown with strained layer superla ttice buffers. A number of electron and hole traps are detected in the material by deep-level transient spectroscopy and photocapacitance ex periments. A particular electron trap with an activation energy of 0.7 6 eV is identified as the main nonradiative center by virtue of the de crease of its density in the same proportion as that of the increase i n luminescence intensity. Density of some other electron traps are als o reduced as a consequence of ALE predeposition. (C) 1996 American Ins titute of Physics.