【International Papers】Structural and Photoelectronic Properties of κ-Ga₂O₃ Thin Films Grown on Polycrystalline Diamond Substrates

      Researchers from the Consiglio Nazionale delle Ricerche (ISM–CNR) have published a dissertation titled "Structural and Photoelectronic Properties of κ-Ga₂O₃ Thin Films Grown on Polycrystalline Diamond Substrates " in Materials.

Abstract

      Orthorhombic κ-Ga₂O₃ thin films were grown for the first time on polycrystalline diamond free-standing substrates by metal-organic vapor phase epitaxy at a temperature of 650 °C. Structural, morphological, electrical, and photoelectronic properties of the obtained heterostructures were evaluated by optical microscopy, X-ray diffraction, current-voltage measurements, and spectral photoconductivity, respectively. Results show that a very slow cooling, performed at low pressure (100 mbar) under a controlled He flow soon after the growth process, is mandatory to improve the quality of the κ-Ga₂O₃ epitaxial thin film, ensuring a good adhesion to the diamond substrate, an optimal morphology, and a lower density of electrically active defects. This paves the way for the future development of novel hybrid architectures for UV and ionizing radiation detection, exploiting the unique features of gallium oxide and diamond as wide-bandgap semiconductors.

Figure 1. (a) Picture of the final device mounted on a PCB. Green light (546 nm wavelength) focused on the interelectrode gap was used for position adjustment before the spectral photoconductivity experiments; (b) Sketch of the operating principle of the device used for spectral photoconductivity experiments. The same device was also employed for current-voltage measurements (in dark conditions) to evaluate the electrical resistivity of the Ga₂O₃ film.

Figure 2. Optical microscopy images of the surface of the naturally-cooled sample: (a) details of the hazy zone (point 1); (b) overall view of the 10 × 10 mm² surface; (c) details of the mixed zone (point 2); (d) details of the mirror-like zone (point 3).

Paper Link：https://www.mdpi.com/1996-1944/17/2/519