近十年来，宽禁带半导体电力电子器件已成为半导体领域的研究重点之一。AlGaN/GaN 肖特基势垒二极管（Schottky Barrier Diode，SBD）具有高压、大电流、大功率的优势，是一种非常有应用前景的电力电子器件。随着GaN基异质结材料生长技术和器件制作工艺不断完善，已有AlGaN/GaN SBD产品问世，但产品技术还远未成熟。本论文主要研究了制作AlGaN/GaN SBD的两个关键问题：表面处理对其欧姆接触的影响和机理，以及肖特基电极的优化和表面态的计算。欧姆接触是影响AlGaN/GaN SBD器件性能的关键因素之一。本论文研究了表面处理对欧姆接触质量的改善及其机理。比接触电阻率的测试结果表明，溶液处理可以降低比接触电阻率，结合XPS测试结果分析得出：溶液表面处理不但能够有效去除AlGaN表面的氧化层，而且能够生成钝化膜，有效降低表面态密度，进而降低电子隧穿势垒的高度，显著改善欧姆接触的质量。肖特基接触电极是AlGaN/GaN SBD中最为关键的工艺，电极尺寸、电极金属和半导体表面性质等都会影响其质量。本论文研究了器件正向导通电流和反向击穿随器件电极尺寸的变化规律，并且比较了Pt和Ni两种不同金属制作的肖特基电极的性能。同时，为了定量地研究表面态对器件性能的影响，本论文提出了一种改进的表面态等价电路模型，并通过实验和理论计算比较了表面处理前后肖特基势垒高度和表面态密度。结果表明，表面处理可以有效提高肖特基势垒高度，降低表面态密度，优化肖特基接触质量。

Recent years, wide band-gap semiconductor power device has become one of the hottest topics in semiconductor field. AlGaN/GaN Schottky Barrier Diode (SBD) is a very promising power device because of its great advantages and potential applications on high power and high voltage devices. Despite of the advancement of the heterostructure growth and the fabrication of devices, it is far from mature. In this article two important issues are studied: one is the effects and mechanism of surface treatments on the ohmic contacts, and the other is the optimization of Schottky electrode and calculation of surface states on the AlGaN surface.Ohmic contact is one of the key factors for fabricating high performance AlGaN/GaN SBD devices. After surface treatments the specific contact resistivity dramatically decreases. To investigate the mechanism of this improvement, the chemical properties of the AlGaN/GaN surface are characterized by using XPS. The results show that surface treatments can not only effectively remove surface oxides, but also form a passivation layer on the surface, which effectively reduces the surface state density to lower the electron tunneling barrier height. Both the two factors contribute to the formation of high quality ohmic contact.Schottky contact is the crucial technology for AlGaN/GaN SBD, which can be affected by electrode size, metals, semiconductor surface properties, etc.. This article studies the rule of forward current and reverse breakdown voltage changing with the electrode size, and a comparison of two different Schottky contact metals Ni and Pt. Meanwhile, in order to quantitatively study the effect of surface state on the performance of AlGaN/GaN SBD, a modified equivalent circuit model for surface states is discussed. The experiment and theoretical calculation results show that surface treatments can effectively optimize the Schottky contact quality by improving the Schottky barrier height and thus reduce surface state density.