SPONTANEOUS FORMATION OF AL RICH AND GA RICH ALXGA1-XAS ALYGA1-YAS SUPERLATTICE AND STRONG ENHANCEMENT OF OPTICAL-PROPERTIES/

Long range composition ordering and spontaneous formation of Al rich a nd Ga rich AlxGa1-xAs/AlyGa1-yAs superlattice were demonstrated. This was observed by cross-sectional transmission electron microscopy (TEM) in a 280 angstrom Al0.4GaAs quantum well laser diode heterostructure with Al0.7GaAs barriers grown on (111)B GaAs substrates. On the contra ry, none of above superstructure was observed by TEM on a side-by-side grown (100) oriented substrate. More evidence is shown in the (111)B Al0.7GaAs barriers which were disordered due to a high growth temperat ure and did not show any superstructure. 10 K photoluminescence was sh own with 32 meV redshift and a 12-times peak intensity enhancement in (111)B orientation. (C) 1994 American Institute of Physics.