Disclosed herein are compositions, methods, and devices. Disclosed herein is a composition comprising a -(Al.sub.xGa.sub.1-x).sub.2O.sub.3, having an x value of less than about 5% and comprising at least one n-carrier dopant. Also disclosed are methods of making the same. Also disclosed are devices comprising the disclosed compositions.

A Schottky barrier diode, including a first n-type semiconductor layer including a -Ga.sub.2O.sub.3-based single crystal epitaxial layer and having a first carrier concentration that determines reverse breakdown voltage and forward voltage, a second n-type semiconductor layer including a -Ga.sub.2O.sub.3-based single crystal substrate and having a second carrier concentration that is higher than the first carrier concentration and determines forward voltage, a Schottky electrode provided on a surface of the first n-type semiconductor layer on the opposite side to the second n-type semiconductor layer, and an ohmic electrode provided on a surface of the second n-type semiconductor layer on the opposite side to the first n-type semiconductor layer. The -Ga.sub.2O.sub.3-based single crystal substrate includes a surface that has a plane orientation rotated by an angle of not more than 37.5 from a (010) plane.