浮结型GaN垂直结构肖特基二极管研究

GaN垂直结构肖特基二极管具有开关速度快、击穿电压高、导通电阻低的优良特性，对于实现紧凑、高效、兼容的功率系统至关重要。传统均匀掺杂的GaN垂直结构肖特基二极管在反偏状态时，其内建电场呈三角形分布。随着反偏电压增加，器件在肖特基接触面处发生提前击穿。为了充分发挥GaN材料高击穿场强的优势，申请人提出采用浮结型GaN垂直结构肖特基二极管方案，改变传统器件反偏时的三角形电场分布，在漂移层中形成两个电场峰值，以增加漂移层的平均击穿场强，提高器件的反向耐压能力。在前期研究中，我们初步生长了浮结型GaN垂直结构肖特基二极管外延结构，研究了p型浮动结的关键参数对器件性能的影响。本项目拟基于前期研究基础，进一步深入研究p型浮动结的界面特性对器件性能的影响机制，建立浮结型GaN肖特基二极管的三维解析模型，制备出高性能的浮结型GaN垂直结构肖特基二极管器件，促进其更快进入新一代高压、大电流功率应用市场。

GaN vertical Schottky diodes feature a fast switching speed, a high breakdown voltage, and a low on-resistance, which is essential for a compact, efficient and compatible power system. Triangular distribution of the built-in electric field is formed when the conventional GaN vertical Schottky diode with a uniform drift layer doping is under reverse bias. A premature breakdown can be observed at the Schottky contact interface with increased reverse bias. In order to take full advantage of the high breakdown strength of the GaN material, we designed a GaN vertical Schottky diode with floating-junction structures, in which the triangular electric field distribution is converted to a two-peak distribution. As a result, the average breakdown strength of the drift layer can be boosted and the breakdown voltage of the devices is increased. In our previous study, we have successfully grown the GaN vertical Schottky diode structure with floating junctions and investigated the impact of the key parameters of the p-type floating junctions on the device performance. Based on our previous results, we are planning to further study the impact of the interface characteristics between the floating junctions and the drift layer on the device performance. A three-dimensional analytical model for the GaN vertical Schottky diodes with floating junctions will be established and high-performance GaN vertical Schottky diodes will also be fabricated, which can promote their applications into the new generation of high-voltage, high-current power markets.