Strain relaxation of Ga/sub 0.2/In/sub 0.8/As and InAs/sub 0.5/P/sub 0.5/ layers grown on InP substrate for 1.6 to 2.4 /spl mu/m spectral range Ga/sub x/In/sub 1-x/As/InAs/sub y/P/sub 1-y//InP photodiodes application

Abstract

Mismatched Ga/sub 1-x/As/InAs/sub y/P/sub 1-y//InP double heterostructures were prepared by the low pressure-metal-organic chemical vapor deposition (LP-MOCVD) epitaxial technique for optical photodiode application in the 1.6 /spl mu/m-2.4 /spl mu/m range. The required narrow band gap active layer consists of a high indium composition Ga/sub 1-x/In/sub x/As (x = 0.8) layer. Different graded composition and superlattice buffer layers are investigated to accommodate the 1.8% lattice mismatch between InP and Ga/sub 0.2/In/sub 0.8/As. It is shown that a two microns thick InAs/sub y/P/sub 1-y/ graded composition layer (y up to 0.5) presents better optical and structural properties than a Ga/sub 1-x/In/sub x/As graded composition layer. High resolution X-ray diffraction investigations of an InAs/sub y/P/sub 1-y//Ga/sub 1-x/I superlattice shows its good ability to act as a barrier to dislocation propagation.<>