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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.

在本项目中，我们研究了以下课题：(1)建立了利用MBE-STM技术实现氮化镓表面表面能量最小化和表面重构的一般原理(2)了解了氮化镓外延层中掺杂和缺陷形成的原子过程。(3)阐明掺杂剂掺入对表面电子性能的影响(4)阐明干蚀刻中的原子过程及其在器件制造中的应用。基于这些结果，讨论了原子相互作用、生长动力学、表面能量学、应变和表面/薄膜电子性能等器件制造的基本过程。我们通过MBE-STM对纤锌矿GaN（0001）的表面重建进行了系统的研究。研究了GaN（0001）表面上的各种重构，并基于STM观测和第一性原理总能量计算的比较，我们提出了一种适用于基本2x2和4x4结构以及其他结构的adatom方案。此外，为了了解纤锌矿GaN干刻蚀过程的原子过程，这对器件应用具有重要意义，我们进行了Cl_2分子热活化干刻蚀GaN表面的STM研究。我们的广泛研究表明，在低温（~ 650C）下，富ga GaN（0001）的主要蚀刻是反阶梯流蚀刻。另一方面，在较高的温度下（~ 700℃），梯田上开始形成三角形的蚀刻坑。它的单步深度意味着双层的双层蚀刻。