Conduction bands in In_1-xAl_xP

Cathodoluminescence (CL) and x-ray emission excited by an electron microprobe in In1-xAlxP at ∼300°K have been monitored simultaneously to yield conduction band structure and alloy composition, respectively. Efficient single-line CL, characteristic of direct bandgap recombination, is observed for x between 0.0 and almost 0.5. Elsewhere, the CL, characteristic of recombination in indirect bandgap semiconductors, is weak. The direct bandgap CL peak has a composition dependence given by hv=1.34+2.23x (eV). The bandgap in the alloy is direct for 0.00≤x<0.44 with a maximum gap of 2.33 eV. © 1970 The American Institute of Physics.