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

9875186这项建议描述了宽禁带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-教室模块的开发，以及协调咨询和推广活动的扩展。由于其大禁带(3.4 eV)，高导热系数和高饱和漂移速度，氮化镓正被广泛应用于各种光电子学和高温、高频和高功率电子器件。最近在GaN外延薄膜质量方面的进展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，我们将研究包括导电层和半导体GaN薄膜在内的新型结构。这项工作将利用GaN的选择性生长及其随后的过度生长来在GaN外延膜中产生嵌入导电层(ECL)。这些结构将在紫外光探测器和可渗透基区晶体管等器件中具有潜在的应用。开发GaN和SiC器件的一个密切相关的挑战是制造具有低比接触电阻率(SCR)的p型欧姆接触。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很大的肖特基势垒高度，即电子在金属-半导体界面上传输的能垒。这些大的势垒高度增加了SCR，即使在相对高掺杂的材料上也是如此。为了降低肖特基势垒高度，将在选定的金属接触和p型GaN或SiC半导体衬底之间以薄(~50-100A)中间层的形式研究InxGa1-xN。氮化铟和氮化镓是完全可溶于彼此的，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InxGal-XN中间层的组成和带隙，人们相信势垒高度可以显著降低。宽禁带半导体技术的长期前景将取决于是否有受过适当教育的毕业生。最近的研究表明，当实验室课程与课堂经验相结合时，学生的学习效果最好。为此，CMU材料科学与工程系计划实施一项新的本科课程，将实验室课程和课堂课程广泛整合。指导性实验的发展对这一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以及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.***