STRAIN DISTRIBUTION IN INP INGAAS SUPERLATTICE STRUCTURE DETERMINED BY HIGH-RESOLUTION X-RAY-DIFFRACTION/

Interfacial strain distribution in a short period InP/InGaAs superlatt ice structure is evaluated by means of high resolution x-ray diffracti on. The diffraction pattern of the structure allows an unambiguous det ermination of interfacial strain distribution. From the numerical calc ulation, positively strained interfacial monolayers at the InP-->InGaA s and negatively strained interfacial monolayers at the InGaAs-->InP i nterfaces had to be introduced in order to reproduce the experimental data. At the InP-->InGaAs interfaces a group V exchange reaction leadi ng to a positively strained InAs or InAs1-xP interfacial layer is comp atible with the simulation. At the InGaAs-->InP interfaces negatively strained ternary or quaternary InGaAsyP1_y meet these requirements. Th e results are consistent with low temperature calorimetric absorption measurements which exhibit a wide band gap InGaAsP-like absorption fea ture at 1.48 eV beyond the InP energy gap.