Electrical and thermal characterisation of liquid metal thin-film Ga$$_2$$O$$_3$$–SiO$$_2$$ heterostructures

Abstract

AbstractHeterostructures of Ga$$_2$$ 2 O$$_3$$ 3 with other materials such as Si, SiC or diamond, are a possible way of addressing the low thermal conductivity and lack of p-type doping of Ga$$_2$$ 2 O$$_3$$ 3 for device applications, as well as of improving device reliability. In this work we study the electrical and thermal properties of Ga$$_2$$ 2 O$$_3$$ 3 –SiO$$_2$$ 2 heterostructures. Here, thin-film gallium oxide with thickness ranging between 8 and 30 nm was deposited onto a silicon substrate with a thermal oxide by means of oxidised liquid gallium layer delamination. The resulting heterostructure is then characterised by means of X-ray photoelectron spectroscopy and transient thermoreflectance. The thin-film gallium oxide valence band offset with respect to the SiO$$_2$$ 2 is measured as 0.1 eV and predicted as $$-2.3$$ - 2.3 eV with respect to diamond. The thin-film’s out-of-plane thermal conductivity is determined to be 3 ±0.5 Wm$$^{-1}$$ - 1  K$$^{-1}$$ - 1 , which is higher than what has been previously measured for other polycrystalline Ga$$_2$$ 2 O$$_3$$ 3 films of comparable thickness.