Materials Processing for Ferromagnetic Wide Bandgap Nitride Heterostructures

该项目将研究先进的材料处理方法，这些方法不会破坏自旋注入和传输，以便在半导体中注入，传输，控制，存储和检测自旋。（In，Mn）As和（Ga，Mn）As中铁磁性的发现为探索高纯异质结构与铁磁性的结合提供了机会。然而，这些材料的低居里温度（分别为35 K和110 K）限制了它们的实际影响;与此形成鲜明对比的是，（Ga，Mn）N预测具有约400 K的TC。该项目将涉及以下主题：（i）开发具有尖锐金属/半导体界面的低电阻p欧姆接触，以允许将自旋极化电流有效注入各种异质结构，例如，(Ga Mn）N/GaN、（Ga，Mn）N/InGaN;（ii）开发用于（Ga，Mn）N和相关材料的等速率和选择性干法蚀刻的适当等离子体化学。对于蚀刻Mn，基于高密度F2的等离子体化学已经是成功的。GaN的正常Cl 2基化学物质将需要改变，以获得在（Ga，Mn）N中的所有三个晶格成分的等速率去除;（iii）选择性区域掺杂中需要的注入/隔离，用于接触形成和器件内的电气和光学隔离。期望使用Si+进行n型掺杂和使用Mg+/P+进行p型掺杂来实现（Ga，Mn）N的有效掺杂。退火过程中的（Ga，Mn）N的热稳定性也将进行探讨，以研究形成其他相或沉淀物;（iv）检查H与Mn的相互作用，如果钝化发生，这将降低TC。的热稳定性的效果，再激活动力学（热和少数载流子注入）和H扩散率，将进行研究;（五）制造各种测试结构，使自旋注入效率的测量，这些包括一个GaMnN/AlGaN/GaN发光二极管和GaMnN spinfet。这项研究的意义将是了解如何处理（Ga，Mn）N以实现有效的自旋注入和输运，作为新型器件结构的基础。该项目涉及具有高度技术相关性的材料科学专题领域的基础研究问题。该研究将在基础层面上为电子/光子器件的重要方面提供基础材料科学知识。从研究中获得的基本知识和理解，预计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理解和基础。 该计划的一个重要特点是通过在一个基本和技术上重要的领域对学生进行培训来整合研究和教育。

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.***