Tilt generation in step-graded In x Ga 1 − x As metamorphic pseudosubstrate on a singular GaAs substrate using a low-temperature grown InGaP interlayer

• Published in: Journal of applied physics 2008-05, Vol.103 (10), p.103527-103527-8
• Main Authors: Ghanad Tavakoli, Shahram, Hulko, Oksana, Thompson, David A.
• Format: Article
• ISSN: 0021-8979; 1089-7550
• DOI: 10.1063/1.2927498

Metamorphic pseudosubstrates of In 0.42 Ga 0.58 As were grown by molecular beam epitaxy using step-graded In x Ga 1 − x As buffer layers grown either directly on a (001) GaAs substrate or on a GaAs substrate overgrown with a layer of low-temperature grown In 0.51 Ga 0.49 P (LT-InGaP). The structures were examined using x-ray reciprocal space mapping to determine the characteristics of the pseudosubstrates and buffer layers. For the sample grown on the LT-InGaP layer, the pseudosubstrate exhibited an asymmetric tilt around [ 1 1 ¯ 0 ] toward the [110] direction. Weak-beam dark-field electron imaging shows an imbalance of misfit dislocations with opposite sign Burgers vector. An explanation for this tilt is given and it is suggested that it may be responsible for the improved quality of epitaxial layers grown on such pseudosubstrates.