β-gallium oxide (β-Ga2O3) has received a considerable attention as the material for high power electronic devices due to its wide bandgap of ~4.9 eV and high thermal and chemical stabilities. Although β-Ga2O3 is not a van der Waals materials like two-dimensional(2D) materials, it can be mechanically exfoliated into thin flakes in the (100) direction because of its monoclinic structure. However, applications of β-Ga2O3 flakes in practical devices could be limited because the thickness of the flakes, which highly affect the electrical performances of devices, is random when obtained by mechanical exfoliation techniques. Therefore, the study of thinning methods to control the thickness of β-Ga2O3 flakes is important to enhance the performances β-Ga2O3-based devices. Photo-enhanced chemical(PEC) etching is an etching process that uses UV irradiation during wet etching. PEC etching not only has the advantages of wet etching such as simplicity, high selectivity, and physical damage-free process but also increases etch rate at room temperature due to the generation of electron-hole pairs.
In this work, we controlled the thickness of β-Ga2O3 flakes using PEC etching process. Unintentionally n-doped flakes were mechanically exfoliated and transferred onto SiO2/Si substrate. The etch rates of β-Ga2O3 flakes depending on the temperature in 85% aqueous H3PO4 solution were obtained without and with UV irradiation. The changes in the morphological, optical, electrical properties of thinned β-Ga2O3 were measured using atomic force microscope, Raman spectroscopy, and semiconductor parameter analyzer. Furthermore, the activation energy was calculated at each etching condition. The details of our experimental conditions and results will be presented at the meeting.