Metal-oxide Semiconductor Field-effect Transistors using Single ZnO Nanowire
- PDF / 238,814 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 96 Downloads / 267 Views
B8.1.1
Metal-oxide Semiconductor Field-effect Transistors using Single ZnO Nanowire Young-Woo Heo1, B.S. Kang2, L.C. Tien1, Y. Kwon1, J.R. La Roche2, B. P. Gila1, F. Ren2, S. J. Pearton1 and D. P. Norton1; 1 Materials Science and Engineering, University of Florida, Gainesville, Florida 2 Chemical Engineering, University of Florida, Gainesville, Florida. ABSTRACT Single ZnO nanowire metal-oxide semiconductor field effect transistors (MOSFETs) were fabricated using nanowires grown by site selective Molecular Beam Epitaxy. When measured in the dark at 25°C,the depletion-mode transistors exhibit good saturation behavior, a threshold voltage of ~-3V and a maximum transconductance of order 0.3 mS/mm .Under ultra-violet (366nm) illumination, the drain-source current increase by approximately a factor of 5 and the maximum transconductance is ~ 5 mS/mm. The channel mobility is estimated to be ~3 cm2 /V.s, which is comparable to that reported for thin film ZnO enhancement mode MOSFETs and the on/off ratio was ~25 in the dark and ~125 under UV illumination. INTRODUCTION There is great current interest in fabrication of ZnO channel thin film transistors for applications in transparent flat panel displays(1-10). Other transparent conducting oxides such as Sn-doped In2O3 , Al-doped ZnO, and Sb-doped SnO2 have been widely applied as transparent electrodes for liquid crystal displays , organic light-emitting diodes , and solar cells (11). ZnO nanowires and nanorods are attracting attention for use in gas, humidity and ultra-violet(UV) detectors (12-14). ZnO is attractive for a broad range of applications in thin film form (15-20), but the ability to make arrays of nanorods with large surface area which has been demonstrated with a number of different growth methods has great potential for new types of transparent electronics that operate with low power requirements (21). Appreciable channel mobilities (25 cm2/V.s) have been obtained in thin film ZnO transistors (1), indicating that even when grown on non-lattice-matched substrates the electrical performance can be impressive. We have previously reported enhancement-mode thin-film metal-oxide semiconductor field-effect transistors (MOSFETs) using phosphorus-doped (Zn,Mg)O channels. The transistors exhibited an on/off ratio of 103 and a channel mobility on the order of 5 cm2/V s, with HfO2 employed as the gate dielectric. There have been initial reports of electrical transport through individual ZnO nanowires. The initial reports show a pronounced sensitivity of the nanowire conductivity to ultraviolet illumination and the presence of oxygen in the measurement ambient (22-24). In this paper we report on the dc performance of single ZnO nanowire MOSFETs using (Ce,Tb)MgAl11O19 gate oxides , measured both in the dark and under UV illumination .We have also fabricated nanowire Schottky diodes,UV detectors and pH sensors ,but will not space kin this paper to discuss those results. Under illumination, both the channel conductivity and maximum transconductance are greatly increased .The
Data Loading...
