Scandium Nitride Crystal Growth and Characterization

非技术描述：氮化钪是一种半导体，像硅一样可以用于电子设备，但很少被研究。该项目专注于制造无缺陷和低杂质浓度的氮化钪单晶，因为这是研究这种材料的内在性质并确定其在发光二极管和高温电子产品等未来器件应用中的潜力所必需的。氮化钪晶体很难生产，因为它的熔化温度很高。这项研究中使用的晶体生长方法，即物理气相传输，比以前使用的方法生产出更大、质量更好的氮化钪晶体。由该项目资助的研究生正在接受实践研究培训，同时做出新的科学发现和开发新技术。该项目还通过K州女孩研究我们的世界暑期讲习班，向年轻妇女(12至14岁)介绍晶体生长和半导体的科学和技术。技术描述：生长没有缺陷或缺陷明显减少的氮化钪(SCN)单晶，以探索这种半导体的本征电学性质。为实现这一目标，本研究的具体活动如下。首先，通过调整炉膛温度、压力和结构来优化物理气相输运生长晶体的过程，以获得低缺陷密度和低杂质浓度的材料。这些实验是由热力学和输运现象模型指导的。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关联，揭示了其导电能量学。具体地说，电子迁移率和载流子浓度由依赖温度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)、与化学计量的偏差和杂质浓度(由二次离子质谱仪测量)相关。第三，故意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)引起的性质差异。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。本研究为今后的器件探索提供了有价值的SCN本征电学性质。

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.