Improvement in the negative bias temperature stability of ZnO based thin film transistors by Hf and Sn doping

• Published in: Thin solid films 2011-08, Vol.519 (20), p.6849-6852
• Main Authors: Kim, Woong-Sun, Moon, Yeon-Keon, Kim, Kyung-Taek, Shin, Sae-Young, Ahn, Byung Du, Lee, Je-Hun, Park, Jong-Wan
• Format: Article
• Language: English
• Subjects: Amorphous oxide semiconductors (AOSs); Applied sciences; Carrier density; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Doping; Electronic structure and electrical properties of surfaces, interfaces, thin films and low-dimensional structures; Electronic transport phenomena in thin films and low-dimensional structures; Electronics; Exact sciences and technology; Hafnium; Hafnium–zinc oxide (HZO); Hafnium–zinc–tin oxide (HZTO); Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Negative bias temperature instability (NBTI); Oxides; Physics; Semiconductor devices; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Theory and models of film growth; Thin film transistors; Thin film transistors (TFTs); Tin; Transistors; Zinc oxide
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2011.01.402

We assessed the performance of ZnO TFTs using Si 3N 4 gate dielectrics after various treatments. A remarkable improvement in the transfer characteristics was obtained for the O 2 plasma treated ZnO TFT and SiO 2 interlayer deposited ZnO TFT. Also, we developed amorphous hafnium–zinc–tin oxide (HZTO) thin film transistors (TFTs) and investigated the influence of hafnium (Hf) doping on the electrical characteristics of the hafnium–zinc oxide (HZO) thin film transistors. Doping with Hf can decrease the carrier concentration, which may result from a decrease of the field effect mobility, and reduce oxygen vacancy related defects in the interfacial layer. Adding tin (Sn) can suppress the growth of a crystalline phase in the HZTO films. The HZTO TFTs exhibited good electrical properties with a field effect mobility of 14.33 cm 2/Vs, a subthreshold swing of 0.97 V/decade, and a high I ON/OFF ratio of over 10 9.