Effect of Growth Pressure on PLD-Deposited Gallium Oxide Thin Films for Deep-UV Photodetectors

Pulsed laser deposition (PLD) is used to grow (2 over bar 01)-oriented single-crystalline beta-gallium oxide (beta-Ga2O3) thin films on c-plane sapphire substrates by optimized growth temperature and pressure. The morphology and crystallinity of the thin films are examined using X-ray diffraction and atomic force microscopy. The thin films are used as the semiconductor layer for metal-semiconductor-metal (MSM) photodetector (PD) devices with various electrode designs. The ultraviolet photodetectors are characterized under 250 nm illumination, showing a high current amplitude increase over dark current conditions that approaches three orders of magnitude at a 6 V bias for an optimized growth pressure of 1 x 10(-3) torr. The photodetectors' transient response is also measured, allowing for the defect analysis to be performed. A peak spectral responsivity of 30.45 A W-1 is measured at 250 nm incident illumination.