UV Response Characteristics of Amorphous Ga<sub>2</sub>O<sub>3</sub> Thin Films With Different Microatom Distributions and a Low-Temperature Fabricated Ultrahigh-Performance a-Ga<sub>2</sub>O<sub>3</sub> UV Detector
Yanghua Chen, Shun Han, Dewu Yue, Ming Fang, Yu Zeng, Wenjun Liu, Peijiang Cao, Deliang Zhu
Abstract
It is very difficult to achieve an ultrahigh response and signal-to-noise ratio in a solar-blind UV (220–280 nm) detector, which is extremely important in its actual applications in many fields (e.g., alarm, biological, and information). Herein, through systematic study on UV response characteristics of amorphous-Ga 2 O 3 (a-Ga 2 O 3 ) films with different microstructures, a simple metal–semiconductor–metal structure detector based on low-temperature (500 °C) fabricated a-Ga 2 O 3 on a fused quartz, with ultrahigh UV response (208563.56 A/W at 250 nm@25 V), low I dark (0.59 pA@25 V), and ultrahigh signal-to-noise ratio (3.40 × 10 9 at 4.3 μW/cm 2 250 nm @25 V) simultaneously, is reported. A new two-step tunneling breakdown mechanism in a-Ga 2 O 3 with a high density of scattered distributed small crystal nanoparticles introduced both ultrahigh UV response and fast speeds (response: t r1: 52.20 μs, t r2: 123.51 μs, recovery: t d1: 1.61 ms, t d2: 33.07 ms) of the device. The high density of the crystal/chaotic interfaces is the main reason for the low I dark and ultrahigh signal-to-noise ratio of the a-Ga 2 O 3 UV detector. In addition, the a-Ga 2 O 3 detector not only has a higher deep-UV response than the crystalline β-Ga 2 O 3 detector but also possesses a much higher signal-to-noise ratio at faint deep-UV light than the complicated MOSFET β-Ga 2 O 3 detector, which makes the low-temperature deposited a-Ga 2 O 3 thin film an ideal material for developing ultrahigh-performance deep-UV detectors.