Homoepitaxial growth of Ge doped <i>β</i>-gallium oxide thin films by mist chemical vapor deposition
Temma Ogawa, Hiroyuki Nishinaka, Kazuki Shimazoe, Tatsuji Nagaoka, Hiroki Miyake, Kazutaka Kanegae, Masahiro Yoshimoto
Abstract
Abstract This study demonstrated homoepitaxial growth of Ge-doped β -Ga 2 O 3 thin films on β -Ga 2 O 3 substrates via mist chemical vapor deposition (CVD) using GeI 4, a water-soluble Ge precursor. The carrier concentration of the Ge-doped β -Ga 2 O 3 thin films was controlled by varying the Ge precursor concentration in the solution. A mobility of 66 cm 2 V −1 s −1 was obtained at a carrier density of 3.4 × 10 18 cm −3 using oxygen carrier gas. X-ray diffraction (XRD) scans 2 θ - ω revealed that homoepitaxial Ge-doped β -Ga 2 O 3 thin films were grown on β -Ga 2 O 3 without phase separation. However, the XRD rocking curves revealed that the mist CVD- grown Ge-doped β -Ga 2 O 3 was degraded compared to the substrate as the Ge concentration increased. The surface morphologies of the Ge-doped β -Ga 2 O 3 exhibited atomically flat surfaces with a root mean square roughness of less than 1 nm. These results indicate that the Ge-doped β -Ga 2 O 3 thin films prepared by mist chemical vapor deposition are promising for device applications.