Materials Processing for Ferromagnetic Wide Bandgap Nitride Heterostructures

该项目将研究先进的材料处理方法，这些方法不会中断自旋注入和传输，以便极化、注入、传输、控制、存储和检测半导体中的自旋。(In，Mn)As和(Ga，Mn)As中铁磁性的发现为探索高纯异质结与铁磁性的结合提供了机会。然而，这些材料的居里温度较低(分别为35K和110K)，限制了它们的实际应用；与之形成鲜明对比的是，(Ga，Mn)N的TC~400K。该项目将涉及以下主题：(I)开发具有尖锐金属/半导体界面的低阻p欧姆接触，以便能够有效地将自旋极化电流注入各种异质结构，例如(Ga，Mn)N/GaN，(Ga，Mn)N/InGaN；(Ii)开发适合于等速率和选择性干法刻蚀(Ga，Mn)N和相关材料的等离子体化学。对于刻蚀锰，基于高密度F2的等离子体化学已经取得了成功。GaN的常规Cl2化学结构将需要改变，以获得(Ga，Mn)N中所有三个晶格成分的等速率移除；(Iii)选择性区域掺杂所需的注入/隔离，以形成接触和器件内电气和光学隔离。用Si+作n型掺杂，用Mg+/P+作p型掺杂，有望实现(Ga，Mn)N的高效掺杂。还将探讨(Ga，Mn)N在热处理过程中的热稳定性，以研究其他相或析出物的形成；(Iv)研究H与Mn的相互作用-如果发生钝化，这将降低TC。将研究该效应的热稳定性、再激活动力学(热效应和少数载流子注入)和氢扩散系数；(V)制作各种测试结构，以测量自旋注入效率-其中包括GaMnN/AlGaN/GaN发光二极管和GaMnN旋转管。这项研究的意义将是加深对如何处理(Ga，Mn)N以实现有效的自旋注入和传输的理解，作为新型器件结构的基础。%该项目解决具有高度技术相关性的材料科学主题领域的基础研究问题。这项研究将在基础水平上为电子/光子器件的重要方面贡献基本的材料科学知识。从研究中获得的基本知识和理解将有助于提高先进器件和电路的性能和稳定性，为设计和生产改进的材料和材料组合提供基本的认识和基础。该计划的一个重要特点是通过在一个具有根本意义和技术意义的领域对学生进行培训，将研究和教育结合起来。

This project will investigate advanced materials processing methods that do not disrupt spin-injection and transport in order to polarize, inject, transport, control, store and detect spins in semiconductors. The discovery of ferromagnetism in (In, Mn)As and (Ga,Mn)As opens an opportunity to explore the combination of high purity heterostructures and ferromagnetism. However the low Curie temperature for these materials (35K and 110K, respectively), limits their practical impact; in sharp contrast, (Ga,Mn)N is predicted to have a TC ~400K. This project will address the following topics: (i) development of low resistance p-ohmic contacts with sharp metal/semiconductor interfaces to allow efficient injection of spin-polarized currents into various heterostructures, e.g., (Ga,Mn)N/GaN, (Ga,Mn)N/InGaN; (ii) the development of appropriate plasma chemistries for equi-rate and selective dry etching of (Ga,Mn)N and related materials. For etching Mn, high density F2-based plasma chemistries have been successful. The normal Cl2-based chemistries for GaN will need to be altered in order to obtain equi-rate removal of all three lattice constituents in the (Ga,Mn)N; (iii) implantation/isolation needed in selective area doping for contact formation and for intra-device electrical and optical isolation. It is expected to achieve efficient doping of (Ga,Mn)N using Si+ for n-type and Mg+/P+ for p-type doping. The thermal stability of the (Ga,Mn)N during annealing will also be explored, in order to study formation of other phases or precipitates; (iv) examine the interaction of H with Mn-if passivation occurs, this will lower TC. The thermal stability of the effect, the reactivation kinetics (both thermal and by minority-carrier injection) and the H diffusivity, will be investigated; (v) fabrication of various test structures to enable a measurement of the spin injection efficiency-these include a GaMnN/AlGaN/GaN light-emitting diode and a GaMnN spinfet. The significance of the research will be the development of an understanding of how to process (Ga,Mn)N to achieve efficient spin injection and transport, as the basis for novel device structures.%%%The project addresses basic research issues in a topical area of materials science having high technological relevance. The research will contribute basic materials science knowledge at a fundamental level to important aspects of electronic/photonic devices. The basic knowledge and understanding gained from the research is expected to contribute to improving the perform-ance and stability of advanced devices and circuits by providing a fundamental understanding and a basis for designing and producing improved materials, and materials combinations. An important feature of the program is the integration of research and education through the training of students in a fundamentally and technologically significant area.***