The electrical properties of Schottky diodes based on MgxZn1-xO thin films deposited by RF magnetron co-sputtering

Abstract

Optoelectronic devices operating in ultraviolet region have attracted much attention in recent years for their potential applications in flame sensing, chemical/biological agents detection, convert communications, missile plume sensing, air and water purification, etc.. Ternary MgxZn1-xO alloy material, with a tunable band gap in the range of 3.37-7.8 eV, is a promising candidate for optoelectronic devices that covers a broad portion of DUV spectrum. Moreover, compared with other wide band gap semiconductors, MgxZn1-xO has various unique features, such as the high resistance to radiation, the amenability to conventional wet chemistry etching, the environmentally friendly characters, and the relatively low growth temperatures. Many methods have been proposed to prepare MgxZn1-xO films, such as chemical vapor deposition, electro-deposition, spray pyrolysis, pulsed laser deposition, the sol-gel method technique, and radio frequency (RF) magnetron sputtering. Among these methods, RF magnetron sputtering is preferred due to its low cost, simplicity, and low process temperature. But up to now, good-quality wurtzite MgxZn1-xO films with high Mg content deposited by RF magnetron co-sputtering are rare. So we used RF

magnetron co-sputtering with ZnO and Mg0.3Zn0.7O targets to deposit wurtzite MgxZn1-xO films on Si substrate. The Mg content could be varied from 0 at.% to 30 at.% by controlling the RF power of Mg0.3Zn0.7O target.

Chapter 1 is the introduction of this study. In chapter 2, the basic properties of ZnO, MgO, and MgxZn1-xO, the application of MgxZn1-xO, the concept of Metal-Semiconductor contact, and the I-V characteristics of Schottky diode were introduced. In chapter 3, the experiment and analysis methods were described. The structural and electrical properties of MgxZn1-xO (0≤x≤0.18) thin films as the function of Mg content were investigated in chapter 4. The Schottky contact properties of MgxZn1-xO thin films with Ag metal as the function of Mg content were studied in chapter 4. The effect of metal materials on Schottky contact properties of Mg0.18Zn0.82O thin film were also investigated in chapter 4. In the final chapter, the results were summarized and concluded.