Here we report that the source of Si impurities commonly observed on (010)
Ξ²βGa2βO3β is from exposure of the surface to air. Moreover, we find that
a 15 minute HF (49%) treatment reduces the Si density by approximately 1 order
of magnitude on (010) Ξ²βGa2βO3β surfaces. This reduction in Si is
critical for the elimination of the often observed parasitic conducting
channel, which negatively affects transport properties and lateral transistor
performance. After the HF treatment the sample must be immediately put under
vacuum, for the Si fully returns within 10 minutes of additional air exposure.
Lastly, we demonstrate that performing a 30 minute HF (49%) treatment on the
substrate before growth has no deleterious effect on the structure or on the
epitaxy surface after subsequent Ga2βO3β growth