Hoonha Jeon

Enhanced Electrical Conductance of ZnO Nanowire FET by Nondestructive Surface Cleaning

Electrical characteristics of zinc oxide nanowire (ZNW) FETs are investigated by nondestructive surface cleaning, ultraviolet irradiation treatment at high temperature and vacuum. UV-light-stimulated oxygen desorption from the active channel improves the device performance of ZNW-FETs. Results show that charge transport in single ZNW strongly depends on its surface environmental conditions and can be explained by formation of depletion layer at the surface by various surface states present on it. The nondestructive surface cleaning removes these absorbed surface states from the nanowire and the current values increase upto ~ 7 muA from ~ 0.4 muA at a bias voltage of 3 V. ZNW-FETs fabricated in this study exhibit mobility of ~ 28 cm2/Vmiddots and a high I ON ne I OFF ratio of ~ 106.

Characteristics of Gallium-Doped Zinc Oxide Thin-Film Transistors Fabricated at Room Temperature Using Radio Frequency Magnetron Sputtering Method

In this paper, we present bottom-gate-type Ga-doped zinc oxide (GZO) thin-film transistors (TFTs) using a certain conventional SiO2 gate insulator by applying a radio-frequency (RF) magnetron sputtering method at room temperature. A low gate leakage current was achieved using this conventional SiO2 gate insulator instead of new gate oxide materials. The root mean square (RMS) value of the GZO film surface was found to be 1.65 nm, and the transmittance was higher than 75% in the visible region. The GZO TFTs operated in a depletion mode with a threshold voltage of -3.4 V. A mobility of 0.023 cm2/(Vs), an on/off ratio of 2×103, and a gate voltage swing of 3.3 V/decade were obtained. We successfully demonstrated that the TFT of depletion-mode type can be fabricated using a GZO film that has good surface uniformity, transparency, and electrical characteristics.

Fabrication and Characteristics of Zinc Oxide- and Gallium doped Zinc Oxide thin film transistor using Radio Frequency Magnetron sputtering at Room Temperature

In this paper we present a bottom-gate type of zinc oxide (ZnO) and Gallium (Ga) doped zinc oxide (GZO) based thin film transistors (TFTs) through applying a radio frequency (RF) magnetron sputtering method at room temperature. The gate leakage current can be reduced up to several ph by applying thermally grown instead of using new gate oxide materials. The root mean square (RMS) values of the ZnO and GZO film surface were measured as 1.07 nm and 1.65 nm, respectively. Also, the transmittances of the ZnO and GZO film were more than 80% and 75%, respectively, and they were changed as their film thickness. The ZnO and GZO film had a wurtzite structure that was arranged well as a (002) orientation. The ZnO TFT had a threshold voltage of 2.5 V, a field effect mobility of , a on/off ratio of , a gate voltage swing of 17 V/decade and it operated in a enhancement mode. In case of the GZO TFT, it operated in a depletion mode with a threshold voltage of -3.4 V, a field effect mobility of , a on/off ratio of and a gate voltage swing of 3.3 V/decade. We successfully demonstrated that the TFTs with the enhancement and depletion mode type can be fabricated by using pure ZnO and 1wt% Ga-doped ZnO.