Investigation on GaAs(0 0 1) surface treated by As-free high temperature surface cleaning method

We have used in in situ scanning tunneling microscopy to study GaAs(0 0 1) surface treated by As-free high temperature surface cleaning method. The temperatures ranged from 575 to 655∘C and an optimum temperature of 605∘C was found. Its surface had ×6×6 structure parallel to [11¯0] direction and smooth morphology by congruent evaporation. However, many pit-like structures formed lower than 600∘C. On the other hand, with 610∘C and higher, the surface became rough, forming many grooves with {111}B and {111}A facets. At 655∘C, the roughness was reduced but the surface easily became milky because of rapid As desorption.