Enhancement of photocurrent and responsivity of Zn_(1-x)Mg_xO (x=15 ) –based ultraviolet detector by UV-Ozone treatment

摘要

UV photodetector have been successfully implemented in various applications like ozone sensing,communication, astronomy and flame detection etc. Zn(Mg)O is a wide band gap material with high excitonic bindingenergy at room temperature thus making it a promising material in optoelectronic industries. In the present work, we areachieving increased photocurrent and high responsivity in UV-A regime with post growth UV-ozone treatment fromphotodetector fabricated using RF sputtered ZnMgO thin film. The thin film was deposited on semi-insulating siliconwafer at 400C for 20 min followed by 70 min UV-Ozone treatment. The final step was to fabricate an interdigitatedelectrode on the processed samples. More than two times enhancement of photocurrent was observed after UVOtreatment. Noteworthy responsivity values of 22 A/W and 67 A/W were measured from as-deposited and UVO annealedphotodetector, respectively at 380 nm with an applied bias of -5 V bias. However, the measured detectivity values for asgrown and UV-O annealed sample was 1.3 x 10~（13） and 2.7 x 10~（13）, respectively. Noise equivalent power in as-depositedsample and UVO treated sample was estimated to be 2.4 ˟ 10~（-12 W/√Hz and 1.1 ˟ 10~（-12） W/√Hz respectively. Photodetector fabricated with UV-O annealing exhibited good switching behaviors with 37 ms and 30 ms rise and fall time,respectively.