The New Wide Band Gap Semiconductor Of Mg <sub> X </ Sub> Of Zn <sub> 1-x </ Sub> O Thin Films Optical Properties Of The Study

ZnO is a versatile material, and has been extensively studied for various applications such as varistors, transducers, transparent conducting electrodes, sensors and catalysts. Otherwise, ZnO is an II-VI wide bandgap semiconductor with a relatively large exciton binding energy and a low pumping threshold at room temperature (RT), and holds a potential for light emitting/detecting or nonlinear optical devices in the blue and UV range.Meanwhile, a heterojunction is one of the key structures for constructing excellent optoelectronic devices using compound semiconductors. Modulating the band gap and keeping the lattice constants similar to each other are essential to construct a heterojunction of two different materials. The bandgap of Mg_xZn_1-xO films can range from 3.3 to 7.9eV because MgO has a bandgap of 7.9eV at RT that is wider than 3.3eV of ZnO at RT. Moreover, Mg_xZn_1-xO films have the wurtzite structure with the low x value. Therefore, Mg_xZn_1-xO has been considered as an appropriate ternary alloy material that can construct efficient heterojunction with ZnO.The goals of this work are to synthesize ZnO and alloys Mg_xZn_1-xO on Si substrates in the forms of thin films by using RF magnetron control sputtering technique and to study the structural, stoichiometric, optical properties of these thin films for the potential applications in the new optoelectronic devices. The main contents include:(1) A brief introduction of the background of ZnO, MgO, Mg_xZn_1-xO and substrate Si materials and a detailed description of the theory and system of RF magnetron control sputtering and the preparation of the films are given.(2) Based on scanning electron microscope (SEM) results, the Mg concentrations in the films are found to be separately 0, 25 and 37 mol.%, which is almost 1.6 times of their respective percentage of MgO in ZnO target. The structure and surface topography of ZnO and Mg_xZn_1-xO alloy thin films on Si substrates are determined by a systematic analysis of X-ray diffraction (XRD) and atom force microscope (AFM). The films are...