EAGER: Collaborative Research: Epitaxial Stabilization of Polar Epsilon-phase Gallium Oxide Thin Films

非技术描述：半导体和铁电材料是无处不在的电子材料。在半导体中，电导率可以通过掺杂来调节，并且用于器件应用的典型半导体中的电荷载流子的速度很大。铁电材料表现出固有的电极化，这种极化可以通过外部电场来逆转；然而，铁电材料中的载流子通常具有较低的电子速度。本研究旨在通过稳定一种新的铁电半导体来将这两种特性结合在一种单一材料中，这种半导体是基于氧化镓的亚稳的epsilon相。这个项目是对表面相氧化镓的结构和合成条件如何影响其材料性能的基本了解的早期努力。理论研究和预测指导了实验工作。通过结合半导体和铁电材料的特性，该项目旨在释放其潜力，前景和限制的多功能设备，如电源，高频和记忆，所有在一个单一的材料平台。该项目为本科生和研究生以及博士后学者提供培训，将理论与建模、先进的材料合成和材料表征协同结合，以发展这一新材料类别的基本结构-性能相关性。技术描述：氧化镓的亚稳的epsilon相被预测是一种稀有的具有超宽禁带的铁电半导体。该项目旨在利用外延技术稳定表观相氧化镓，并演示极性域的电场转换。本研究采用第一性原理密度泛函理论计算和金属-有机气相外延相结合的方法，在不同的预测衬底上生长氧化镓薄膜，并对其质量进行控制。它使用各种表征技术，包括像差校正的扫描电子显微镜，来表征沉积的薄膜的结构、电学、光学和极性性质，并建立结构-性质-加工关系。基于epsilon相氧化镓的高质量铁电半导体的实现有望为设计用于电力和高频电子、信息存储和处理应用的新型器件开辟道路。教育和外展方面包括对本科生和研究生的培训，以及为犹他州地区学校的高中生和教师组织暑期项目，以提供接触纳米技术的机会。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical description: Semiconductors and ferroelectrics are ubiquitous electronic materials. In semiconductors, the conductivity can be tuned using doping and the velocity of charge carriers in typical semiconductors used for device applications is large. Ferroelectric materials exhibit inherent electric polarization that can be reversed using an external electric field; however charge carriers in ferroelectrics typically have lower electron velocity. This research aims at combining both the properties in a single material by stabilizing a new ferroelectric semiconductor based on the metastable, epsilon phase of gallium oxide. This project is an early effort on developing a fundamental understanding of how the structure and synthesis conditions of epsilon-phase gallium oxide affects its material properties. Theoretical studies and predictions guide the experimental efforts. By combining the properties of semiconductors and ferroelectrics in epsilon-phase gallium oxide, this project aims to unlock its potential, prospects and limitation for devices with multiple functionalities, such as power, high frequency, and memory, all in a single materials platform. The project provides training to undergraduate and graduate students and a post-doctoral scholar to synergistically combine theory and modeling, advanced material synthesis, and materials characterization to develop fundamental structure-property correlations in this new class of materials. Technical description: The metastable, epsilon phase of gallium oxide has been predicted to be a rare, ferroelectric semiconductor with an ultra-wide band gap. This project seeks to stabilize epsilon-phase gallium oxide using epitaxy and demonstrate electric-field switching of polar domains. The research employs a combination of first-principles density-functional theory calculations and metal-organic vapor phase epitaxy to grow epsilon gallium oxide thin films on various predicted substrates and control their quality. It uses a variety of characterization techniques, including aberration-corrected scanning transmission electron microscopy, to characterize the structure, electrical, optical and polar properties of the deposited thin-films and develop structure-property-processing correlations. The realization of high-quality ferroelectric semiconductor based on epsilon-phase gallium oxide is expected to open up pathways to design novel devices for power and high-frequency electronics, information storage and processing applications. Education and outreach aspects include training of undergraduate and graduate students and the organization of a summer program for high-school students and teachers from Utah-region schools to the Utah Nanofab and epitaxy facility to provide exposure to nanotechnology.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.