Direct growth of GaAs-based structures on exactly (001)-oriented Ge/Si virtual substrates: reduction of the structural defect density and observation of electroluminescence at room temperature under CW electrical injection

The effects of atomic layer epitaxy (ALE) on the surface Morphology, the antiphase boundaries (APBs) and the dislocation density of GaAs grown on exactly (001)-oriented Ge/Si virtual substrates (VS) have been investigated. ALE combined with the insertion of a low temperature (<500degreesC) GaAs buffer layer led to a drastic reduction of the APBs and of the dislocation density (<5 x 10(5) cm(-2)), and to a reduction of the surface roughness, thus leading to an important improvement of the photo luminescence yield of InGaAs quantum well (QW) based structures. Light emitting diodes (LEDs) containing InGaAs/GaAs QWs have been realised on exactly (00 I)-oriented Ge/Si VS. We observed room-temperature continuous wave operation from these LEDs. (C) 2004 Elsevier B.V. All rights reserved.