Influence of chemical etching on step bunching formation on GaAs (100) during thermal oxide removal

We report on the influence of the chemical etching in the step bunching formation on GaAs (100) 0.2o off and GaAs (100) 2o off toward <010> surfaces after the oxide desorption process of the substrates at high temperatures under an H2 ambient. The step bunches were observed by in-air atomic force microscopy. Our results reveal that step bunches were formed only on chemically etched samples desorbed under an As4 overpressure using H2 as the carrier. When GaAs substrates without chemical etch were deoxidized the step bunches were not observed in despite of the H2/As4 presence. From the results we conclude that the chemical etching strongly influence the step bunching formation