Characterization of GaAs/Al/sub x/Ga/sub 1-x/As structure using scanning photoluminescence

The number of usable devices that can be obtained from an epitaxially-grown structure is often dependent on the uniformity of the growth on the wafer. Thus the spatial uniformity of an epitaxial growth and its relationship to growth conditions have been issues of continuing interest. Here, an apparatus for measuring the photoluminescence over an entire wafer is described. A specific example, the use of this data to relate indium coverage on the back surface of MBE-grown material to the properties of the epitaxial layers, is then discussed. A clear correlation between the details of the indium coverage and the local growth rate on the front surface of the wafer is found.