Surface segregation during reactive etching of GaAs and InP

Abstract
We have studied the surface composition of gallium arsenide and indium phosphide under conditions of physical sputtering and reactive ion beam etching. Samples of Fe‐doped (100) GaAs and InP were bombarded with 1‐keV Ne+ ions under a varying amount of Cl2 dose. Low‐energy ion scattering spectroscopy and sputtered neutral mass spectrometry indicate an increase of the Group V element at the surface upon addition of Cl2 to the system. This effect is believed to be due to segregation of the As and P due to an altered chemical potential at the surface/vacuum interface resulting from chlorine adsorption. The segregation and subsequent volatilization of PClx species leaves aggregates of In/InClx species at the surface, resulting in a roughened surface.

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