InAs epitaxial lateral overgrowth of W masks

The conditions for successful epitaxial lateral overgrowth of W patterns by InAs using low-pressure metalorganic vapour phase epitaxy were studied. The substrates used were InAs (0 0 1) wafers and the range of growth temperatures between 500 and 600 °C. The selective growth was investigated as a function of the V/III-ratio on W-ring test structures and wires oriented in different directions. 100-nm-wide wires, oriented in 30° off from the [11̲0]-direction, were completely covered with InAs without any void formation and the surface was planarized after deposition of 350 nm at the V/III-ratio of 14. Wires oriented along the [11̲0]-direction were found to effectively block the lateral overgrowth by the formation of mesa ridges limited by {1 1 0} and {1 1 1}A-planes for V/III-ratios between 14 and 56. All other grating directions showed limited lateral growth. This observed orientation dependence is in general agreement with the overgrowth of GaAs, but shows differences compared to InP.