Deep-Level Traps Responsible for Persistent Photocurrent in Pulsed-Laser-Deposited β-Ga2O3 Thin Films

Gallium oxide (β-Ga2O3) is emerging as a promising wide-bandgap semiconductor for optoelectronic and high-power electronic devices. In this study, deep-level defects were investigated in pulsed-laser-deposited epitaxial films of β-Ga2O3. A deep ultraviolet photodetector (DUV) fabricated on β-Ga2O3 film showed a slow decay time of 1.58 s after switching off 250 nm wavelength illumination. Generally, β-Ga2O3 possesses various intentional and unintentional trap levels. Herein, these traps were investigated using the fractional emptying thermally stimulated current (TSC) method in the temperature range of 85 to 473 K. Broad peaks in the net TSC curve were observed and further resolved to identify the characteristic peak temperature of individual traps using the fractional emptying method. Several deep-level traps having activation energies in the range of 0.16 to 1.03 eV were identified. Among them, the trap with activation energy of 1.03 eV was found to be the most dominant trap level and it was possibly responsible for the persistent photocurrent in PLD-grown β-Ga2O3 thin films. The findings of this current work could pave the way for fabrication of high-performance DUV photodetectors.