Investigation of gallium oxide thin film hetero-integrated with bulk diamond via atomic layer deposition.

[Display omitted] • A comprehensive investigation of Ga 2 O 3 /diamond heterostructures, including microstructure, chemical state, and thermal conductance characteristics, was conducted by combining theory with experiments. • Deep etching analysis revealed the presence of a non-diamond sp2 peak near the interface of the heterostructure. • The heterostructure exhibited a staggered (type Ⅱ) band alignment. • The thermal conductivity of amorphous Ga 2 O 3 was 5.13 W/(m·K) and the TBC of Ga 2 O 3 /diamond was 19.22 MW/(m2·K) from TDTR measurements. In this work, the characteristics of the gallium oxide (Ga 2 O 3)/diamond heterostructure were thoroughly examined after the preparation of Ga 2 O 3 thin film on bulk diamond via atomic layer deposition. The X-ray diffraction (XRD) analysis revealed the Ga 2 O 3 film amorphous and diamond polycrystalline. The atomic force microscopy (AFM) mapping displayed remarkably smooth surfaces of the Ga 2 O 3 film and diamond substrate (RMS of 0.184 and 0.508 nm, respectively). The scanning electron microscopy (SEM) images showed conspicuous grains formed on the diamond, and small crystallites on the surface of the film. The optical characteristics were investigated via spectroscopic ellipsometry (SE) and UV/Vis/NIR spectrophotometer. Raman spectroscopy suggested a sharp diamond-related (sp3) peak and an extremely weak bulge band around 1350–1620 cm−1. X-ray photoelectron spectroscopy (XPS) analysis indicated Ga 2 O 3 /diamond heterojunction to be staggered (type II) band alignment with valence band and conduction band offsets of around 1.18 eV and 2.09 eV, respectively. Moreover, according to time-domain thermoreflectance (TDTR) measurements, the thermal conductivity of Ga 2 O 3 and the thermal boundary conductivity of the heterointerface were 5.13 W/(m·K) and 19.22 MW/(m2·K), respectively. These findings not only demonstrate the feasibility of Ga 2 O 3 -on-diamond hetero-integration but open up new prospects for the design and physical analysis of Ga 2 O 3 /diamond-based devices in the future. [ABSTRACT FROM AUTHOR]