In-situ etch to improve chemical beam epitaxy regrown AlGaAs/GaAs interfaces for HBT applications

We have studied the etching effect of AlxGa1-xAs (0 less than or equal to x less than or equal to 0.5) by trisdimethylaminoarsenic (TDMAAs) at different substrate temperatures, and the quality of the resulting etched/regrown GaAs interface. We find that the etching rate of AlxGa1-xAs decreases with increasing Al composition, and the interface trap density of the TDMAAs etched/regrown interface can be reduced by about a factor of 10 as deduced from capacitance-voltage carrier profiles. A smooth surface morphology of GaAs with an interface state density of 1.4x10(11) cm(-2) can be obtained at a lower in-situ etching temperature of 550 degrees C. Moreover, by using this in-situ etching the I-V characteristics of regrown p-n junctions of Al0.35Ga0.65As/Al0.25Ga0.75As and Al0.35Ga0.65As/GaAs can be improved.