Layers were grown by metal-organic molecular beam epitaxy, from trimethylgallium and As2, onto (001)-oriented substrates at 450 or 500C. The (2 x 4) surface reconstruction was then observed by using high-energy electron diffraction techniques. Post-growth infra-red measurements, using polarized light, demonstrated that a C-H complex which gave rise to a vibrational absorption at 2688/cm was aligned along the [110] direction, perpendicular to the [¯110] direction of the surface As dimer bond. After H passivation in a plasma, this absorption disappeared, but was regenerated by annealing at 450C in a vacuum. It was concluded that the observations confirmed a previous attribution of the 2688/cm defect to an H-(CAs)2 complex.

B.R.Davidson, R.C.Newman, T.Kaneko, O.Naji: Physical Review B, 1994, 50[16], 12250-3