Integrate high Z and low Z compound semiconductors for 60 keV spectrometry

非技术：放射性同位素的检测和鉴定对国家安全和医学成像具有重要意义。不同的同位素可以通过它们在放射性衰变过程中发出的伽马射线的能量来相互区分。高效、高分辨率的伽马射线探测需要具有高原子序数(Z)的半导体。然而，这些材料具有较低的带隙，基于这些材料的器件具有很高的电子噪声。在这种探测器的结合区中的高电场显著地增加了这种噪声。因此，精密辐射探测器需要大量的冷却来降低电子噪音。所需的大范围冷却既昂贵又不可靠。研究人员建议在室温下以紧凑的封装实现高能量分辨率的伽马射线探测。这些探测器将集成高Z低带隙半导体和低Z高带隙半导体。高Z材料有效地探测伽马射线，低Z材料在高场区域提供低电子噪声。这种方法利用了这两种材料的相对优势。该团队带来了世界知名的半导体材料生长和伽马射线探测器制造方面的专业知识，以应对与该项目相关的挑战。多学科研究团队在投资于代表性不足的少数族裔研究生和本科生研究人员(包括女性)方面有着既定的记录。这项拟议的工作将成为加州大学洛杉矶分校一个新项目的基础，在该项目中，学生们将参加跨学科的研讨会和实验室之旅。该计划旨在弥合材料科学、电气工程和生物医学物理之间的差距。技术：基本需要紧凑、低功率和高分辨率的辐射探测器，能够在室温附近工作，为民用安全、辐射监视和放射成像应用提供X射线到伽马射线能谱。通过结合世界知名的III-As/Sb结构外延生长和器件制造、传感器件和伽马射线探测方面的专业知识，该项目计划在紧凑的封装中实现对60keV伽马射线的直接探测，能量分辨率为1%。提出了一种新型的高原子序数(Z)伽马射线吸收体与低噪声结区的集成，以构建一种能量敏感的辐射探测器，该探测器将利用两种材料的相对优势，实现低背景噪声的高能量分辨率伽马射线探测。该技术方法的设计和组织是为了实现整合伽马射线探测器结构的概念，并将对对X射线和伽马射线光谱学领域至关重要的材料和设备参数进行全面的实验研究。团队集合了独特的经验和知识组合，以应对与该项目相关的挑战。更广泛的影响在一定程度上来自研究团队的多学科性质，该团队有投资于代表性不足的少数族裔研究生和本科生研究人员(包括女性)的既定记录。这项拟议的工作将成为加州大学洛杉矶分校一个新项目的基础，在该项目中，学生们将参加跨学科的研讨会和实验室之旅，旨在弥合材料科学、电气工程和生物医学物理之间的差距。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:The detection and identification of radioactive isotopes is important for national security and medical imaging. Different isotopes can be distinguished from one another by the energy of gamma rays that they emit during radioactive decay. Efficient, high-resolution detection of gamma rays requires semiconductors with high atomic number (Z). However, these materials have low band-gaps and device based on such materials have high electronic noise. A high electric field in the junction regions of such detectors significantly increases this noise. Precision radiation detectors therefore require significant cooling to reduce electronic noise. The extensive cooling required can be both expensive and unreliable. The investigators propose to achieve gamma-ray detection with high energy resolution in a compact package at room temperature. These detectors will integrate a high-Z low band-gap semiconductor with a low-Z, high band-gap semiconductor. The high-Z material detects gamma rays efficiently and the low-Z material provides low electronic noise in the high field region. This approach exploits the relative benefits of the two materials. The team brings world-renowned expertise in growth of semiconductor materials and fabrication of gamma-ray detectors to bear on the challenges associated with this project. The multidisciplinary research team has an established track record of investing in underrepresented minority graduate students and undergraduate researchers, including women. The proposed work will form the basis for a new program at UCLA in which students take part in cross-disciplinary workshops and laboratory tours. This program aims to bridge the gaps between material science, electrical engineering, and biomedical physics.Technical:A fundamental need exists for compact, low-power and high-resolution radiation detectors that can operate near room temperature to provide X-ray to gamma-ray spectroscopy for civil security, radiation surveillance, and radiological imaging applications. By combining world-renowned expertise in epitaxial growth and device fabrication of III-As/Sb structures, sensing devices, and gamma-ray detection, this project plans to achieve direct detection of 60 keV gamma-rays with energy resolution 1% in a compact package. A novel integration of high atomic number (Z) gamma-ray absorbers with low-noise junction regions is proposed to construct an energy-sensitive radiation detector that will exploit the relative benefits of the two materials, to achieve high energy resolution gamma-ray detection with low background noise. The technical approach is designed and organized to achieve the concept of integrating gamma ray detector structures, and will deliver comprehensive experimental investigations of material and device parameters that are of fundamental importance to the field of X-ray and gamma-ray spectroscopy. A team is brought together with a unique combination of experience and knowledge to bear on the challenges associated with this project. The broader impacts arise in part from the multidisciplinary nature of the research team, which has an established track record of investing in underrepresented minority graduate students and undergraduate researchers, including women. The proposed work will form the basis for a new program at UCLA in which students take part in cross-disciplinary workshops and laboratory tours aimed at bridging the gaps between material science, electrical engineering, and biomedical physics.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.