Surface height modulation in strain relaxation and its smoothing using solid state crystallization in InAs quantum-well growth on GaAs

Relaxation of lattice-mismatch strain in the epitaxial growth of InAs quantum-well structures on GaAs substrates produces height modulations on the surface. The surface meandering is known as the cross-hatch pattern that appears generally in the highly lattice-mismatched growth of (001)-oriented cubic crystals. We show that the magnitude of the height modulation in molecular beam epitaxy is reduced by incorporating a layer prepared using solid state crystallization. The surface morphology is also shown to become irregular or even checker-board-like when the relaxation is caused immediately by an abrupt composition change. We demonstrate a method for localizing threading dislocations in the buffer layer in such a circumstance. Electron mobility increases for the quantum wells prepared on the abruptly-relaxed buffer layer.