alloy thin films*

Ultra-wide bandgap (UWBG) semiconductors, whose bandgap is wider than 3.4 eV, have been gaining attentions as promising materials for future power-electronics devices. As a novel UWBG material, rutile-structured germanium oxide (r-GeO₂) has emerged due to its theoretically excellent properties^[1], that is, ambipolar dupability, high carrier mobility, and high thermal conductivity as well as its wide bandgap of 4.68 eV^[2]. In addition, by realizing an alloy system of rutile-structured r-SnO₂-r-GeO₂-r-SiO₂, bandgap engineering and an application of the heterostructures to power devices can be possible in the future. Recently, growth of r-GeO₂ thin film has been reported^[3,4].

In this work, we demonstrate r-(Ge_x,Sn_1-x)O₂ alloys in an entire Ge composition range (x=0.00, 0.37, 0.55, 0.82, and 1.00) by mist chemical vapor deposition. Physical and chemical properties at each x are measured by spectroscopic ellipsometry and X-ray photoelectron spectroscopy, respectively. These achievements advance the application of r-(Ge,Sn)O₂/r-GeO₂ heterostructures.

 

[1] Chae et al., APL 118, 260501 (2021).

[2] Stapelbroek et al., SSC 25, 959 (1978).

[3] Chae et al., APL 117, 072105 (2020).

[4] Takane et al, APL 119, 062104 (2021).