In situ electrochemical scanning tunneling microscopy (STM) was employed for observing GaAs semiconductor electrodes in an aqueous sulfuric acid solution. Well-ordered surfaces were prepared by chemical etching in a mixed solution of H2SO4 and H2O2. Atomically flat terrace-step structures were consistently observed on the chemically etched GaAs(111)A surface in 0.05M H2SO4. Atomic steps observed in the STM images correspond to the double layer step with a height of 0.33 nm. Atomic images of the Ga-terminated GaAs(111) surface were successfully obtained under electrochemical conditions for the first time. The STM images reveal a hexagonal structure with an interatomic distance of ∼ 0.4nm. The results presented here clearly demonstrate that the ideal GaAs(111)A-(1 × 1) structure exists for several hours in a pure H2SO4 solution in a cathodic potential region.
- Gallium arsenide
- Low index single crystal surfaces
- Scanning tunneling microscopy
- Semiconductor-electrolyte interfaces
- Solid-liquid interfaces
- Surface chemical reaction
- Surface structure