Heteroepitaxy of GaAs on Si and tensile strain effects on acceptor activation energy

Epitaxial GaAs layers have been grown on Si substrates by metalorganic chemical vapor deposition. The GaAs surface dislocation density estimated by a molten KOH study is as low as 4x10 ⁵ cm ^-2 when using InGaAs/GaAs strained-layer superlattice and 5 /im-thick Ge buffer layer. The full width at half maximum of (400) double crystal x-ray diffraction shows 98 arc seconds. Residual stress in GaAs layers is investigated using low temperature photoluminescence. The origins of defect-related extrinsic lines appeared in low temperature (5 K) photoluminescence are figured out by the theoretical formula based on 2-band model. We also found the carbon acceptor binding energy is reduced by 4.1 meV under 0.294% biaxial tensile strain comparing with unstrained homoepitaxial GaAs layers.