Deposition of highly resistive, undoped, and p-type, magnesium-doped gallium nitride films by modified gas source molecular beam epitaxy

Undoped, highly resistive (≳102 Ω cm) and Mg-doped, p-type (0.3 Ω cm) monocrystalline GaN films with a thickness of (4–5)×103 Å have been achieved via modified gas source molecular beam epitaxy on AIN buffer layers without the post-processing procedures of either electron beam irradiation or annealing necessary in chemical vapor deposition (CVD) derived films. The carrier concentrations and mobilities could not be accurately measured in the undoped films; values to 1018 cm−3 and 10 cm2/V s, respectively, have been achieved in the p-type films. These results indirectly support the hypothesis of Mg-H complexes as the cause of the difficulty in achieving highly conducting p-type materials using CVD techniques.