Influences of substrate surface orientation on misfit accommodation in InGaP/GaAs heterostructures

Abstract

The effect of crystallographic tilt of the substrate on the misfit strain and stress are investigated in this study. InGaP/GaAs heterostructure wafers are grown on two types of substrates with normal [100] orientation and 7 ° (±0.2 °) tilted from [100] toward [110] orientation. Lattice mismatches are measured using 511 asymmetric and 400 symmetric reflections. The lattice misfits and the elastic strains are also measured. The elastic strain-lattice misfit relation shows that larger strain is developed in the layers grown on the tilted substrate. The radius of curvature, R, plotted as a function of lattice misfit reveals that larger R, in general, is obtained from the sample with smaller misfit. It also shows that R is smaller in the tilted sample even when the lattice misfit is identical to that of the normal sample. It is also found that the misfit stress is larger in the tilted sample. The results presented show that the characteristics of misfit accommodation are improved in the layers grown on the tilted substrate.