Surface two-dimensional hole gas in Si doped β-Ga2O3 thin film

Although two-dimensional electron gases have been realized in a number of semiconductor surfaces, examples of two-dimensional hole gases (2DHG) - the counterpart to 2DEG - are still very limited. Besides, owing to the deep energy level nature of potential dopants, achieving acceptor p-type β-Ga2O3 is a well-known challenge so far. In this work, we report what appears to be an exceptional p-type 2DHG surface on a Si-doped monoclinic (010) β-Ga2O3 crystal which otherwise is n-type in the bulk. The majority of the free carries at the surface have been determined to be holes with a sheet concentration of p ∼ 8.7 × 1013 cm−2 and a puzzlingly high mobility value of µh ∼ 80 cm2/(V·s) at room T.