Role of Schottky barrier height at source/drain contact for electrical improvement in high carrier concentration amorphous InGaZnO thin film transistors. (October 2015)

• Record Type: Journal Article
• Authors: Trinh, Thanh Thuy; Jang, Kyungsoo; Velumani, S.; Dao, Vinh Ai; Yi, Junsin
• Is Part Of: Materials science in semiconductor processing. Volume 38(2015:Oct.)
• Page Start: 50
• Page End: 56
• Publication Date: 2015-10
• Subjects: Schottky barrier modification -- High-conductivity IGZO-TFT -- High mobility TFTs; Semiconductors -- Periodicals; Integrated circuits -- Materials -- Periodicals; Semiconducteurs -- Périodiques; Circuits intégrés -- Matériaux -- Périodiques; Electronic journals; 621.38152
• DOI: 10.1016/j.mssp.2015.03.051
• Languages: English
• ISSNs: 1369-8001

Abstract

Abstract: We report the fabrication of bottom-gate thin film transistors (TFTs) at various carrier concentrations of an amorphous InGaZnO (a-IGZO) active layer from ~10 16 to ~10 19 cm −3, which exceeds the limit of the concentration range for a conventional active layer in a TFT. Using the Schottky TFTs configuration yielded high TFT performance with saturation mobility ( μ sat ), threshold voltage ( V TH ), and on off current ratio ( I ON / I OFF ) of 16.1 cm 2 /V s, −1.22 V, and 1.3×10 8, respectively, at the highest carrier concentration active layer of 10 19 cm −3 . Other carrier concentrations (<10 19 cm −3 ) of IGZO resulted in a decrease of its work function and increase in activation energy, which changes the source/drain (S/D) contact with the active layer behavior from Schottky to quasi Ohmic, resulting in achieving conventional TFT. Hence, we successfully manipulate the barrier height between the active layer and the S/D contact by changing the carrier concentration of the active layer. Since the performance of this Schottky type TFT yielded favorable results, it is feasible to explore other high carrier concentration ternary and quaternary materials as active layers.