HREM study of strained CdTe layer on rough GaAs(001) substrate grown by hot wall epitaxy

Abstract

The interface structure and strain relief mechanisms of CdTe/GaAs(001) grown by hot wall epitaxy were examined by high-resolution electron microscopy. The interface structure was determined for the GaAs surface which, as viewed in the [110] direction, was much rougher than in the [1&1bar;0] direction. The interface in the [1&1bar;0] cross-section is characterized with fluctuating misalignments across the film, a large quantity of planar defects and 60° type dislocations. Contrastingly in the [110] cross-section, the defect density was considerably decreased on the vicinal of interface. The misfit dislocations are mainly of Lomer types. Moreover, the strain retained in CdTe film at a thickness of about 1–2 μm in both cross-sections is the order of 10⁻³. However, the strain in [110] cross-section is larger than that in the [110] cross-section. The mechanism for these differences is also discussed.