Type-I band offset between diamond and <i>n</i>-type Al Ga oxynitride: Possible diamond-based heterojunction for high-power and high-frequency electronic devices

In an attempt to realize diamond-based p–n heterojunctions for high-power and high-frequency electronic devices, fabrication and characterization of heterojunctions of wurtzite oxynitride of AlGaON(0001) layers on diamond (111) substrates were performed. Thin layers of oxynitride of AlON (2 nm) and AlGaON (15–100 nm) were fabricated on a diamond (111) substrate using remote RF plasma with a source gas of N2(99%) and O2(1%) and Knudsen effusion sources of Al and Ga, and a solid source of Si (n-type dopant). Atomic force microscopy, reflection high energy electron diffraction, high-resolution transmission electron microscopy (TEM) images, and energy dispersive spectroscopic spectra in TEM of the oxynitride layers showed an epitaxial growth to the substrate with grain sizes of 10–100 nm. X-ray photoelectron spectroscopy results of the AlON (2 nm) and AlGaON (15 nm) layers revealed favorable type-I band alignments toward the diamond substrate. Hall-effect measurements showed an n-type nature of AlGaON(100 nm) layers and ∼1000 times larger conductivity than that of the highest conducting n-type diamond. Thus, the possibility of diamond-based p–n heterojunction for high-power and high-frequency electronic devices is shown.