Scandium Nitride Crystal Growth and Characterization

非技术描述：氮化钪是一种半导体，它像硅一样可以用于电子器件，但很少被研究。该项目的重点是制造无缺陷和低浓度杂质的氮化钪单晶，因为这对于研究这种材料的内在特性和确定其在未来器件应用（如发光二极管和高温电子器件）的潜力是必要的。氮化钪晶体由于其很高的熔化温度而难以生产。在本研究中使用的晶体生长方法，物理蒸汽传输，产生更大，质量更好的氮化钪晶体比以前采用的方法。本项目支持的研究生在进行新的科学发现和开发新技术的同时，接受实践研究训练。该项目还通过“K-State Girls research Our World”夏季讲习班，向12至14岁的年轻女性介绍晶体生长和半导体的科学技术。技术描述：培养无缺陷或缺陷显著减少的氮化钪（ScN）单晶，以探索这种半导体的固有电学特性。为实现这一目标，研究的具体活动如下：首先，通过调整炉内温度、压力和结构，优化物理气相输运晶体生长过程，生产出低缺陷密度和低杂质浓度的材料。这些实验以热力学和输运现象模型为指导。其次，测量了ScN的电学性质，并将其与温度和杂质浓度进行了相关性分析，揭示了ScN的导电特性。具体来说，电子迁移率和载流子浓度由温度相关的霍尔效应测量确定，并与晶体缺陷密度（由缺陷敏感蚀刻确定）、化学计量偏差和杂质浓度（由二次离子质谱测量）相关。第三，有意地将选定的杂质添加到氮化钪中，以确定它们如何改变其电学性质。研究了晶体取向和极性（氮或钪）引起的性能差异。通过将这些测量与工艺条件相关联，控制ScN电性能的方法正在开发中。这项研究为未来的器件探索提供了有价值的ScN固有电学性质。

Nontechnical Description: Scandium nitride is a semiconductor, which like silicon can be used for electronic devices, but has rarely been studied. This project focuses on making single crystals of scandium nitride that are free of defects and with low concentrations of impurities, as this is necessary for studying intrinsic properties of this material and determining its potential for future device applications such as light emitting diodes and high-temperature electronics. Scandium nitride crystals have been difficult to produce because of its very high melting temperatures. The crystal growth method used in this research, physical vapor transport, produces larger, better quality scandium nitride crystals than previously employed methods. Graduate students supported by this project are receiving hands-on research training while making new scientific discoveries and developing new technologies. This project also introduces young women (12 to 14 years old) to the science and technology of crystal growth and semiconductors, through the K-State Girls Researching Our World summer workshops. Technical Description: Single crystals of scandium nitride (ScN) with no or significantly fewer defects are grown to explore the intrinsic electrical properties of this semiconductor. To achieve this goal, the specific activities of the research are as follows. First, the process of crystal growth by physical vapor transport is optimized by adjusting the furnace temperature, pressure, and configuration to produce material with low defect densities and low impurity concentrations. These experiments are guided by thermodynamic and transport phenomena modeling. Second, the electrical properties of ScN are measured and correlated with the temperature and impurity concentrations, to reveal its electrical conduction energetics. Specifically, the electron mobility and charge carrier concentrations are determined by temperature-dependent Hall effect measurements and are correlated with the crystal defect densities (determined by defect sensitive etching), deviations from stoichiometry, and impurity concentrations (measured by secondary ion mass spectrometry). Third, selected impurities are intentionally added to scandium nitride to determine how they change its electrical properties. Differences in the properties caused by the crystal orientation and polarity (nitrogen or scandium) are investigated. By correlating these measurements with the process conditions, methods of controlling ScN's electrical properties are under development. This study provides valuable intrinsic electrical properties of ScN for future device explorations.