In this study we have investigated, for the first time, the morphological and electrical properties of the in-situ etched/regrown interfaces of GaAs and AlxGa1-xAs using tris-dimethylaminoarsenic (TDMAAs) in a chemical beam epitaxy (CBE) chamber. The TDMAAs in-situ etching condition of GaAs is optimized according to the analysis of atomic force microscopy (AFM) and capacitance-voltage (C-V) carrier profiles. The TDMAAs etch rate of GaAs increases from 40 to 135 nm/h by increasing the substrate temperature from 550°C to 700°C, but the etched surface morphology of GaAs on a patterned substrate becomes rougher at higher etching temperatures. A smooth surface morphology of GaAs with an interface state density of 1.4 × 1011 cm-2 can be obtained at a lower in-situ etching temperature of 550°C. TDMAAs is shown to be an effective and promising precursor for in-situ etching of GaAs, thus providing a clean etched/regrown interface for novel device applications.