Defects Analysis in Strained InAlAs and InGaAs Films Grown on (111)B InP Substrates

We have examined the structure of InGaAs and InAlAs strained monolayers grown by MBE on (111)B, 1-deg off toward -2 1 1-line InP substrates. TEM and AFM observations have revealed the bunching of InAlAs surface steps. The film exhibits structural inhomogeneities and threading dislocations induced by the coalescence of misorientation steps. The characterizations performed on the InGaAs film have shown periodically contrasted domains developing in the direction of growth. From similar results obtained on InP(100)-based growth, we have interpreted these variations to be composition modulation involved in the tensile strain-relaxation process. Also, InAs epitaxy performed on the InAlAs top-surface has demonstrated that the first stages of growth were proceeding at the bunched step edges, following a 3D mechanism. (Author)