[E-6] Advanced Oxide Sensors

[E-6-05] The use of local etching and NiO capping layer to improve the performance of ultraviolet photodetectors based on SiZnSnO thin film transistors

〇Wen-Hung Lai¹, Wei-Wen Chen¹, Rong-Ming Ko², Chao-Yen Chang¹, Chien-Hung Wu³, Shui-Jinn Wang¹ (1. Inst. of Microelectronics, Dept. of Electrical Eng., Univ. of National Cheng Kung University (Taiwan), 2. Academy of Innovative Semiconductor and Sustainable Manufacturing, Univ. of National Cheng Kung University (Taiwan), 3. Dept. of Optoelectronics and Materials Eng., Chung Hua University (Taiwan))

Presentation style: Online

https://doi.org/10.7567/SSDM.2022.E-6-05

The use of a thick channel layer (Tch) with a locally etched region and a NiO capping layer (CL) thereon to release the trade-off between the dark current (Idark) and photo current (Iph) of UV photodetector based on SZTO TFT is demon-strated. The influences of the Tch and final thickness (Tchf) af-ter local etching, and NiO CL on the optoelectrical properties of SZTO TFTs are investigated. Experimental results show that the 100-nm-thick SZTO TFT with a Tchf of 40 nm and a NiO CL has excellent in Rph and Sph up to 1972 A/W and 1.9×10^7 A/A under UV irradiation at 275 nm, which are about 303 and 251 times larger than the conventional 30-nm-thick SZTO TFT. It’s attributed to the use of a thick Tch and the formation of NiO CL/SZTO pn heterojunction maximize the harvest of photogenerated carriers to cause more negative ΔVth of TFT to boost Iph under UV irradiation, in addition, a thin effective Tch obtained from the local etching together with NiO CL is very effective in lowing Idark.