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Atomic-scale investigation and its device application for GaN crystal growth

GaN晶体生长的原子尺度研究及其器件应用

基本信息

批准号：
11355002
负责人：
SAKURAI Toshio
金额：
$ 22.53万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

In this project, we have studied on the following subjects as listed below; (1) establishing the general principles for the surface energy minimization and surface reconstruction of GaN surface by MBE-STM (2) understanding the atomistic process for the dopant incorporation and defect formation in GaN epitaxial layers. (3) clarifying the effect of dopant incorporation on the surface electronic properties (4) clarifying the atomistic process in dry etching and its application for the device fabrication. Based on those results, atomic interaction, growth dynamics, surface energetics, strain, and surface/film electronic properties, etc. which are the fundamental process for device fabrication, have been discussed.We have performed systematic investigations of surface reconstructions on Wurtzite GaN(0001) by MBE-STM. Various reconstructions on the GaN(0001) surface are studied and based on the comparison between the STM observations and first-principles total energy calculations, we propose an adatom scheme for the basic 2x2 and 4x4 structures, and others as well. Also, in order to understand atomistic process underlying dry etching processes of Wurtzite GaN, which is of great important for device application, we have carried out STM study of thermally activated dry etching of GaN surface by Cl_2 molecules. Our extensive studies show that at low temperature (〜650C) the dominated etching of Ga-rich GaN(0001) is anti-step-flow etching. On the other hand, at the higher temperature(〜700C), triangular etching pits on terraces start to form. Its single-step depth implies the bilayer-by-bilayer etching.

在本计画中，我们进行了以下的研究：（1）建立利用分子束外延扫描隧道显微镜（MBE-STM）进行氮化镓表面能最小化与表面重建的一般原则;（2）了解氮化镓磊晶层中掺杂物的掺入与缺陷形成的原子过程。(3)阐明了掺杂剂掺入对表面电子性质的影响。（4）阐明了干法刻蚀中的原子化过程及其在器件制造中的应用。在此基础上，讨论了器件制备的基本过程--原子间相互作用、生长动力学、表面能、应变和表面/薄膜电子性质等，并利用MBE-STM对纤锌矿GaN（0001）表面重构进行了系统的研究。研究了GaN（0001）表面的各种重构，并基于STM观测结果与第一性原理总能量计算结果的比较，提出了一种适用于基本2x2和4x 4结构的吸附原子方案。同时，为了更好地理解纤锌矿GaN干法刻蚀过程中的原子化过程，对器件的应用具有重要意义，我们对Cl_2分子热激活干法刻蚀GaN表面进行了STM研究。我们的大量研究表明，在低温（~ 650 ℃）下，富Ga GaN（0001）的主要刻蚀是反阶梯流刻蚀。另一方面，在较高的温度下（约700 ℃），在梯田上开始形成三角形蚀坑。其单步深度意味着双层对双层的蚀刻。