氮化镓电子器件三元氮化物低界面态密度栅介质及钝化介质研究

Gan-based power devices have become an important development direction of the internationally recognized next-generation power semiconductor devices, and many research institutions and enterprises have been engaged in the research and development of this field. With the continuous improvement of technology, the GaN-based power devices have exceeded the Si base power devices in terms of switching speed and resistance of the conductor, and have been tested in some power systems. However, the GaN base power device has not yet entered the practical stage, and one of the important factors is the stability and reliability of the interface state. This project presents a method of medium growth without surface damage. By using the laser molecular beam epitaxy (LMBE) technology, a new type of tri-nitride medium is explored to meet the above requirements. The influence mechanism of the interface state between the pure semiconductor surface and the media is studied through the related performance characterization. The ultimate goal is to obtain the high quality of the new dielectric layer of nitride, which can reduce the interface state density of the AlGaN/GaN HEMTs device to 10^(11)eV^(-1)cm^(-2), so as to improve the reliability and stability of the device.

GaN基功率器件已成为国际公认的下一代功率半导体器件的重要发展方向，国内外众多研究机构与企业已投入到这一领域的研发中。随着技术的不断进步，GaN基功率器件已经在开关速度及比导体电阻等方面超过了Si基功率器件，并且在一些电力系统中试用了。可是GaN基功率器件目前还没有真正进入实用化阶段，其中一个重要因素是界面态引起的稳定性及可靠性问题。本项目提出了无表面损伤的介质生长方法，利用激光分子束外延（LMBE）技术，探索满足以上要求的新型三元氮化物介质的生长方法，并通过相关性能表征研究纯净半导体表面与介质之间形成界面态的影响机理。为最终获得高质量的三元氮化物新型介质层，使得AlGaN/GaN HEMTs器件界面态密度降低到10^(11)eV^(-1)cm^(-2)，从而提高器件的可靠性和稳定性打下一定的基础。

本项目开展三元氮化物新型介质层对AlGaN/GaN HEMTs器件界面特性的影响，通过对降低或消除界面态对AlGaN/GaN HEMTs器件电学特性的影响研究，从而提高器件的可靠性和稳定性，使其满足电力电子市场的实际应用需求。根据原有基础和相关条件，重点研究AlBN、AlZrN两种三元氮化物材料的生长机制，基于PLD技术对AlBN、AlZrN进行了系统的生长参数优化，包括：衬底温度、生长压强、激光能量、靶间距、原位退火温度、退火时间等参数；利用AFM、SEM、TEM、XPS等一系列测试表征方法，对介质层与本体材料界面的质量、界面态、介质的缺陷和陷阱等进行相关表征研究，获得相关的物理参数。开展了GaN HEMT器件的新工艺与结构研究，包括：常关型器件新技术、表面处理及界面插入技术等；将AlBN介质薄膜应用于GaN HEMT，研制了AlBN介质栅GaN HEMT和AlBN钝化GaN HEMT两种器件，经IV、CV等手段测试，AlBN介质能有效改善器件界面态密度，提高了器件饱和电流、跨导，降低了导通电阻。研究结果达到了预期目标：研究证实AlBN介质能有效改善器件界面态密度，使界面态密度降低到10的11次方量级，提高了器件的可靠性和稳定性，提高了器件饱和电流、跨导，降低了导通电阻。