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

提案编号：2048390（牵头），2048397& 2048400主要研究者：Amirhossein Goldan（PI），Ayaskanta Sahu（Co-PI）&Dragica Vasileska（Co-PI）标题：合作研究：具有高K电介质阻挡层的固态硒光电倍增器，用于高、无噪声雪崩增益机构：纽约的州立大学斯托尼布鲁克（牵头），纽约大学&亚利桑那州立大学非技术摘要由于单晶半导体中高度随机的碰撞电离过程，无定形硒是唯一的无序半导体，产生雪崩倍增增益，同时表现出非常低的过量噪声因子，由于非弹道和单载流子碰撞电离。该项目的主要目标是通过充分利用非晶硒通过具有高介电常数的溶液处理氧化物阻挡层的确定性雪崩倍增特性来制造和表征高灵敏度固态光电倍增管。从理论的角度来看，空穴碰撞电离过程的无噪声性质将在非晶硒中建模，以增强对无序结构中热载流子输运的科学见解。由此产生的技术可用于广泛的先进领域和应用，如医疗诊断成像，高能物理，切伦科夫成像探测器和跟踪器，光通信和时域光谱。这个项目的更广泛的影响包括在这个令人兴奋的研究领域培训学生（研究生、本科生和未充分代表的学生），以及在线传播工具和材料。技术摘要非晶硒准备通过其无噪声单载波雪崩倍增增益来彻底改变固态光电探测和成像。目前，为了实现高动态范围和线性模式操作，用于低光检测的检测器几乎完全由真空光电倍增管制成，其中仅存在电子并且由倍增器电极确定性地倍增。然而，光电倍增管体积庞大，在可见光谱中的量子效率差，并且不能制成成像阵列。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质，信噪比的增强量通常受到过量噪声的严重限制。因此，最佳信噪比通常出现在非常低的增益下。这项工作提出了一个真正的固态替代真空光电倍增管使用非晶硒作为体雪崩i层，这是一种独特的无序光敏材料。在这种非晶硒层中，空穴载流子传输可以完全从局部状态转移到扩展状态，其中空穴经历确定性和非马尔可夫碰撞电离雪崩。为了在器件和成像器中利用这种材料特性，并且为了在没有不可逆击穿的情况下实现可靠且可重复的雪崩增益，需要非绝缘的n型空穴阻挡/电子传输层。这项工作提出了使用室温下，溶液处理的量子点，作为高k电介质空穴阻挡n层。胶体量子点的溶液合成允许高质量的化学计量和无空位的晶体，其具有在所需的反向偏置p-i-n结构中室温沉积的潜力，而不诱导无定形硒的任何结晶，与其他不相容的高温制造技术相反。这种方法首次实现了使用固态材料达到10 E6或更高的雪崩增益。应创建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，将开发一个用于模拟通过缺陷运输的内部动力学蒙特卡罗代码。 接下来，一个内部的全波段蒙特卡罗模拟器，利用硒的全波段结构，将建立检查散装硒中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结合计算机辅助设计模拟，为更有效的硒光电倍增管的制造提供设计指导。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.