Collaborative Research: Solid-State Selenium Photo-multiplier with a High-K Dielectric Blocking Layer for High, Noise-free Avalanche Gain

建议编号：2048390(牵头)，2048397&2048400主要研究员：Amirhossein Goldan(PI)，Ayaskanta Sahu(Co-PI)&Amgica Vasileska(Co-PI)标题：合作研究：带高K介质阻挡层的固态硒光电倍增器用于高，无噪音的雪崩晶体管机构：纽约州立大学石溪分校(领先)，纽约大学和亚利桑那州立大学非技术摘要由于单晶半导体中的高度随机碰撞电离过程，寻找一种模拟经典真空光电倍增管行为的固态光电探测器一直是人们长期追求的目标。由于非弹道和单载流子碰撞电离，非晶态硒是唯一一种产生雪崩倍增增益的无序半导体，同时表现出非常低的过剩噪声系数。该项目的主要目标是通过溶液处理的高介电常数氧化物阻挡层，充分利用非晶态硒的确定性雪崩倍增特性来制备和表征高灵敏度的固态光电倍增管。从理论上讲，空穴碰撞电离过程的无噪声特性将在无定形硒中模拟，以增强对无序结构中热载流子输运的科学洞察力。由此产生的技术可用于医疗诊断成像、高能物理、切伦科夫成像探测器和跟踪器、光通信和时间域光谱分析等广泛的先进领域和应用。该项目的更广泛影响包括在这一激动人心的研究领域对学生(研究生、本科生和未被充分代表的学生)进行培训，以及在线传播工具和材料。技术摘要无形态硒将通过其无噪声的单载流子雪崩倍增效应，彻底改变固态光探测和成像技术。目前，为了实现高动态范围和线性模式的工作，用于微光探测的探测器几乎全部由真空光电倍增管组成，在真空光电倍增管中，只有电子存在，并被动态极确定地倍增。然而，光电倍增管体积庞大，在可见光光谱下量子效率较低，无法制成成像阵列。虽然固态晶体半导体也被用作雪崩光电二极管，但由于雪崩碰撞电离过程的随机性，信噪比的提高往往受到过量噪声的严重限制。因此，最佳信噪比通常在非常低的增益下出现。这项工作提出了一种真正的固态替代真空光电倍增管，使用非晶态硒作为体雪崩I层，这是一种独特的无序光敏材料。在这种非晶硒层中，空穴载流子输运可以完全从局域态转变为扩展态，此时空穴经历了确定性和非马尔科夫碰撞电离雪崩。为了在器件和成像器中利用这种材料特性，并在不发生不可逆击穿的情况下获得可靠和可重复的雪崩增益，需要一种非绝缘的n型空穴阻挡/电子传输层。这项工作提出使用室温、溶液处理的量子点作为高k介电空穴阻挡n层。与其他不相容的高温制备技术不同，胶体量子点的溶液合成允许高质量的化学计量比和无空位的晶体，具有在所需的反向偏置p-i-n结构中室温沉积的潜力，而不会导致任何非晶态硒的晶化。这种方法首次能够使用固态材料达到10E6或更高的雪崩增益。应建立探索空穴阻挡层物理特性的计算模型，以了解和优化器件性能。为此，将开发用于模拟通过缺陷的输运的内部动力学蒙特卡罗程序。下一步，将建立一个室内全能带蒙特卡罗模拟器，利用硒的全能带结构来研究块状硒的空穴碰撞电离过程。作为最后一步，动力学和全波段蒙特卡罗结果将用于计算机辅助设计模拟，为制造更高效的硒光电倍增管提供设计指南。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。

Proposal Number: 2048390 (Lead), 2048397 & 2048400Principal Investigator: Amirhossein Goldan (PI), Ayaskanta Sahu (Co-PI) & Dragica Vasileska (Co-PI)Title: Collaborative Research: Solid-State Selenium Photo-multiplier with a High-K Dielectric Blocking Layer for High, Noise-free Avalanche GainInstitution: State University of New York Stony Brook (Lead), New York University & Arizona State UniversityNontechnical AbstractThe search for a solid-state photodetector that mimics the behavior of a classical vacuum photomultiplier tube has been a long-standing quest because of the highly stochastic impact ionization process in single-crystalline semiconductors. Amorphous selenium is the only disordered semiconductor that produces avalanche multiplication gain while exhibiting a very low excess noise factor due to non-ballistic and single-carrier impact ionization. The primary objective of this project is to fabricate and characterize high sensitivity solid-state photomultipliers by fully exploiting the deterministic avalanche multiplication properties of amorphous selenium via a solution-processed oxide blocking layer with a high dielectric constant. From the theoretical perspective, the noise-free nature of the hole impact ionization process will be modeled in amorphous selenium to enhance scientific insight into hot carrier transport in disordered structures. The resulting technology can be utilized in a wide range of advanced fields and applications such as medical diagnostic imaging, high energy physics, Cherenkov imaging detectors and trackers, optical communications, and time-domain spectroscopy. The broader impact of this project involves training of students (graduate, undergraduate, and under-represented) in this exciting field of research, and dissemination of tools and materials online.Technical AbstractAmorphous selenium is poised to revolutionize solid-state photodetection and imaging through its noise-free single-carrier avalanche multiplication gain. Currently, to achieve high dynamic range and linear mode operation, the detectors used for low-light detection are almost exclusively made of vacuum photomultiplier tubes, where only electrons exist and are multiplied deterministically by the dynodes. However, photomultiplier tubes are bulky, have poor quantum efficiency in the visible spectrum, and cannot be made into an imaging array. Although solid-state crystalline semiconductors are also used as avalanche photodiodes, the amount of enhancement in signal-to-noise ratio is often severely limited by excess noise due to the stochastic nature of the avalanche impact ionization process. Thus, the optimal signal-to-noise ratio typically occurs at very low gains. This work proposes a true solid-state alternative to the vacuum photomultiplier tube using amorphous selenium as the bulk avalanche i-layer, which is a unique disordered photosensing material. In this amorphous selenium layer, hole carrier transport can be shifted entirely from localized to extended states, where holes experience deterministic and non-Markovian impact ionization avalanche. To utilize this material property in devices and imagers, and to achieve reliable and repeatable avalanche gain without irreversible breakdown, a non-insulating n-type hole-blocking/electron-transporting layer is required. This work proposes use of room-temperature, solution-processed quantum-dots, as the high-k dielectric hole-blocking n-layer. Solution synthesis of colloidal quantum dots allows for high-quality stoichiometric and vacancy-free crystals with potential for room-temperature deposition in the desired reverse-biased p-i-n structure, without inducing any crystallization of amorphous selenium, as opposed to other incompatible high-temperature fabrication techniques. This methodology enables, for the first time, reaching an avalanche gain of 10E6 or beyond using a solid-state material. Computational models that explore the physics of the hole blocking layers shall be created to understand and optimize device performance. To this effect, an in-house kinetic Monte Carlo code used to model transport through defects will be developed. Next, an in-house full-band Monte Carlo simulator, that utilizes the full band structure of selenium, will be established to examine the hole impact ionization process in bulk selenium. As a final step, the kinetic and the full-band Monte Carlo results will be coupled for computer-aided design simulations, to provide design guidelines for the fabrication of more efficient selenium photomultipliers.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.