STRUCTURAL AND OPTICAL-PROPERTIES OF GAXIN1-XP LAYERS GROWN BY CHEMICAL BEAM EPITAXY

Chemical beam epitaxial (CBE) GaxIn1-xP layers (x approximate to 0.5) grown on (001) GaAs substrates at temperatures ranging from 490 to 580 degrees C have been investigated using transmission electron diffract ion (TED), transmission electron microscopy, and photoluminescence (PL ). TED examination revealed the presence of diffuse scattering 1/2 {11 1}(B) positions, indicating the occurrence of typical CuPt-type orderi ng in the GaInP CBE layers. As the growth temperature decreased from 5 80 to 490 degrees C, maxima in the intensity of the diffuse scattering moved from 1/2{111}(B) to 1/2{-1+delta,1-delta,0} positions, where de lta is a positive value. As the growth temperature increased from 490 to 550 degrees C, the maxima in the diffuse scattering intensity progr essively approached positions of 1/2{(1) over bar 10}, i.e., the value of delta decreased from 0.25 to 0.17. Bandgap reduction (similar to 4 5 meV) was observed in the CBE GaInP layers and was attributed to the presence of ordered structures.