CAREER: Investigation of Novel Structures and Associated Interfaces for Wide Bandgap Semiconductor Devices

该提案描述了宽带隙半导体器件的新结构和金属化的研究，与半导体和薄膜科学相关的集成实验室-教室模块的发展，以及协调咨询和推广活动的扩展。由于氮化镓的大带隙（3.4 eV）、高导热性和高饱和漂移速度，氮化镓被广泛应用于各种光电和高温、高频、大功率电子器件中。近年来氮化镓外延膜质量的进步促使人们努力开发可用于制造高效器件的结构。在这个项目中，将研究由导电层和半导体GaN薄膜组成的新型结构。这项工作将采用氮化镓的选择性生长及其随后的过度生长来在氮化镓外延膜内产生嵌入式导电层（ECL）。这些结构将在诸如紫外线光电探测器和可渗透基极晶体管等器件中具有潜在的应用。GaN和SiC器件发展的一个密切相关的挑战涉及具有低比接触电阻率（scr）的p型欧姆触点的制造。由于这些半导体的大带隙和大功函数，p型材料上的金属接触产生了大的肖特基势垒高度，或电子在金属-半导体界面上传递的能量势垒。即使在相对高掺杂的材料上，这些大势垒高度也增加了scr。为了降低肖特基势垒高度，将在选定的金属触点和p型GaN或SiC半导体衬底之间以薄层（~50-100 A）的形式研究InxGa1-xN。氮化铟和氮化镓彼此完全可溶，因此InxGa1-xN的组成可以在从纯GaN到纯InN的范围内变化。通过改变lnxGal-XN中间层的组成和带隙，可以显著降低势垒高度。宽带隙半导体技术发展的长期前景将取决于受过适当教育的毕业生的可用性。最近的研究表明，当实验课程与课堂体验相结合时，学生学得最好。因此，CMU材料科学与工程系计划实施一种新的本科课程，广泛整合实验室和课堂课程。开展有指导意义的实验对该计划的成功实施至关重要。该提案讨论了开发选定的实验室模块和扩展学生咨询和外展计划的计划

9875186PorterThis proposal describes research on novel structures and metallizations for wide bandgap semiconductor devices, the development of integrated laboratory-classroom modules associated with semiconductors and thin film science, and the extension of coordinated advising and outreach activities.Due to its large bandgap (3.4 eV), high thermal conductivity, and high saturation drift velocity, gallium nitride is being intensively pursued for a variety of optoelectronic and high temperature, high frequency, and high power electronic devices. Recent advances in the quality of GaN epitaxial films have prompted efforts to develop structures which can be used in making efficient devices. In this project novel structures comprising conducting layers and semiconducting GaN films will be investigated. This work will employ the selective growth of GaN and its subsequent overgrowth to produce embedded conducting layers (ECL) within the GaN epitaxial films. These structures will have potential applications in devices such as ultra-violet photodetectors and permeable base transistors.A closely related challenge for the development of both GaN and SiC devices involves the fabrication of p-type ohmic contacts with low specific contact resistivities (SCRs). Because of the large bandgaps and large workfunctions of these semiconductors, metal contacts on p-type material yield large Schottky barrier heights, or energy barriers for electron transport across the metal-semiconductor interface. These large barrier heights increase SCRs even on relatively highly doped material. To reduce the Schottky barrier heights InxGa1-xN will be investigated in the form of thin (~50-100 A) interlayers between selected metal contacts and the p-type GaN or SiC semiconductor substrates. Indium nitride and gallium nitride are completely soluble in one another, such that the composition of InxGa1-xN may be varied over the range from pure GaN to pure InN. By varying the composition, and thus the bandgap, of the lnxGal-XN interlayer, it is believed that the barrier heights can be significantly reduced.The long-term outlook for the advancement of wide bandgap semiconductor technology will depend on the availability of suitably educated graduates. Recent research indicates that students learn best when laboratory courses are integrated with classroom experiences. For this reason the Materials Science & Engineering Department at CMU plans to implement a new undergraduate curriculum with extensive integration of laboratory and classroom courses. The development of instructive experiments will be critically important to the successful implementation of this program. This proposal discusses plans for developing selected laboratory modules and expanding student advising and outreach programs.***