Source/drain metallization effects on the specific contact resistance of indium tin zinc oxide thin film transistors. (November 2015)

• Record Type: Journal Article
• Authors: Nguyen, Cam Phu Thi; Trinh, Thanh Thuy; Raja, Jayapal; Le, Anh Huy Tuan; Lee, Youn-Jung; Dao, Vinh Ai; Yi, Junsin
• Is Part Of: Materials science in semiconductor processing. Volume 39(2015:Nov.)
• Page Start: 649
• Page End: 653
• Publication Date: 2015-11
• Subjects: ITZO-based TFT -- S/D electrodes -- Specific contact resistance -- TLM mask; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2015.05.069
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: We report on the specific contact resistance of interfaces between thin amorphous semiconductor Indium Tin Zinc Oxide (ITZO) channel layers and different source/drain (S/D) electrodes (Al, ITO, and Ni) in amorphous oxide thin film transistors (TFTs) at different channel lengths using a transmission line model. All the contacts showed linear current–voltage characteristics. The effects of different channel lengths (200–800 μm, step 200 μm) and the contact resistance on the performance of TFT devices are discussed in this work. The Al/ITZO TFT samples with the channel length of 200 μm showed metallic behavior with a linear drain current-gate voltage ( I D – V G ) curve due to the formation of a conducting channel layer. The specific contact resistance ( ρ C ) at the source or drain contact decreases as the gate voltage is increased from 0 to 10 V. The devices fabricated with Ni S/D electrodes show the best TFT characteristics such as highest field effect mobility (16.09 cm 2 /V·s), ON/OFF current ratio (3.27×10 6 ), lowest sub-threshold slope (0.10 V/dec) and specific contact resistance (8.62 Ω·cm 2 at V G =0 V). This is found that the interfacial reaction between Al and a-ITZO semiconducting layer lead to the negative shift of threshold voltage. There is a trend that the specific contact resistance decreases with increasing the work function of S/D electrode. This result can be partially ascribed to better band alignment in the Ni/ITZO interface due to the work function of Ni (5.04–5.35 eV) and ITZO (5.00–6.10 eV) being somewhat similar.