Se passivation and regrowth of ZnSe(001) epilayers on GaAs(001)

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Abstract
We report the use of a Se overlayer to passivate and protect the surface of ZnSe epilayers during prolonged exposure to atmosphere. The samples were grown by molecular-beam epitaxy (MBE) on GaAs (001) substrates and passivated by the deposition of a Se coating near room temperature before removal from the MBE system. The Se coating is readily desorbed in ultrahigh vacuum at substrate temperatures of 115–150 °C. The resultant single-crystal surfaces are clean, stoichiometric, and well ordered, as demonstrated by Auger electron spectroscopy and reflection high-energy electron diffraction. Regrowth of ZnSe on these surfaces yields epilayers which exhibit excellent crystalline order comparable to that of continuously grown reference samples, as shown by x-ray double-crystal rocking curves. This Se passivation technique offers a simple means of transferring such II-VI epilayers through atmosphere from the growth system to other facilities while preserving surface single-crystal order and cleanliness.