PASSIVATION OF GAAS(111)A SURFACE BY CL TERMINATION

It is found that an ordered and air‐stable GaAs(111)A–(1×1)–Cl surface can be produced by chemical etching/passivation with dilute HCl solution. The synchrotron polarization‐dependent Cl K‐edge x‐ray absorption near‐edge structure and x‐ray photoelectron spectroscopy studies showed that the surface is terminated with Ga–Cl bonds oriented along the surface normal. Low‐energy electron diffraction studies showed a bulklike (1×1) structure on the Cl‐terminated GaAs(111)A surface. The Cl termination eliminates surface band‐gap states caused by surface oxides. Photoluminescence measurements showed a dramatic increase in the near‐band radiative emission rate corresponding to reduction in the occupied surface band‐gap states. A reduction of surface gap states by Cl termination was confirmed by surface photovoltage measurements.