ORIENTATION RELATIONSHIP OF ALIGNED CARBON-HYDROGEN COMPLEXES IN GAAS FORMED BY THE DECOMPOSITION OF TRIMETHYLGALLIUM TO THE DIRECTIONS OF THE (2X4) SURFACE RECONSTRUCTION OBSERVED DURING GROWTH

GaAs layers have been grown by metal-organic molecular-beam epitaxy from trimethylgallium and cracked arsenic (As2) on (001)-oriented substrates held at 450 or 500°C, and the directions of the (2×4) surface reconstruction observed by high-energy electron diffraction were marked. Postgrowth infrared measurements using polarized light demonstrated that a carbon-hydrogen complex giving vibrational absorption at 2688 cm-1 was aligned along the [110] direction, perpendicular to the [1̄10] direction of the surface arsenic dimer bond. After hydrogen passivation in a plasma, this absorption was lost but was regenerated by annealing samples at 450 °C in a vacuum. The observations confirm a previous assignment of the 2688-cm-1 defect to a H-(CAs)2 complex. © 1994 The American Physical Society.