Band Engineering for High Gain Digital III-V Avalanche Photodiodes

非技术性：雪崩光电二极管(APD)被广泛用于将光学数据转换为电信号，并且可以在广泛的应用中使用。这些领域包括光纤通信、医学光谱、红外传感，以及需要高增益和高带宽的应用，如量子信息网络。APDS通过在器件的高电场区域进行内部增益和载流子倍增，提供了非常高的灵敏度。然而，这种收益是以增加散粒噪声为代价的。噪声是由于分离的电子和空穴电流通过复杂的反馈机制耦合而产生的。在保持增益的同时限制噪声的一种方法是将一种类型的载波限制在较窄的带宽内，以便总体载波倍增主要保持单极。这项建议侧重于数字III-V异质结的能带工程，它可以在一个能带内选择性地创建小禁带，从而限制相应的载流子能量并减少散粒噪声。PIS将对基于高铝含量数字III-V合金的APDS中的材料物理和界面化学进行详细的计算和实验研究。该提议的成功实施将扩大稳定的III-V合金的材料基因组，并制定高增益光电二极管的设计规则。这些“设计”的APD在波长从3微米到5微米的关键电信频谱中的噪声将降低10到20倍，并能够进行单光子探测。调查人员将把结果纳入即将到来的课程和书籍中。他们还将通过各种方案和奖学金从代表性不足的群体中招募学生和教师。结果将通过附属的合作研究中心在与行业和政府成员举行的会议和会议上公布。技术：这项提议将导致对III-V合金的能带形成和轨道化学进行基础研究，从而控制载流子电离系数、过量噪声和雪崩光电二极管(APD)的整体光电器件设计和降噪。该提案将涉及为III-V合金APD的电子和光学传输开发多尺度计算模型，并为高增益的低噪声APD制定设计规则。实验将集中在数字和随机III-V APD的制备和表征，具有不同的材料组成、取向、温度、周期和粗糙度分布，以及对其电子和光学性质的测量，以证实理论研究的预测并分离竞争机制的影响。利用这些结果，我们将制作一种分离的吸收电荷倍增(SACM)雪崩光电二极管，以结合不同的合金化吸收和倍增需求，以及高速的改进型单行载流子(MUTC)光电二极管，以探测载流子饱和速度。最终目标将是以每秒25千兆位和每秒50千兆位的速度运行，从而实现高性能每秒100千兆位和每秒400千兆位的粗波分复用以太网。改进APD在光子探测方面的性能将打开它们在商业、军事和研究领域的广泛应用。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。

Nontechnical:Avalanche photodiodes (APDs) are widely used to convert optical data into electrical signal and can be used in a wide range of applications. These include optical fiber communication, medical spectroscopy, infrared sensing, and applications needing high gains and bandwidth such as quantum information networks. APDs provide very high sensitivity through internal gain and carrier multiplication in a region of high electric field in the device. This gain, however, comes at the cost of increased shot noise. The noise arises due to the pair creation by separate electron and hole currents that couple through a complex feedback mechanism. One way to limit the noise while preserving the gain is to constrain one type of carrier to a narrow bandwidth so that overall carrier multiplication stays primarily unipolar. This proposal focuses on band engineering of digital III-V heterostructures that can create minigaps selectively inside one band, thereby constraining the corresponding carrier energy and reducing shot noise. The PIs will undertake a detailed computational and experimental study of the materials physics and interface chemistry in APDs based on digital III-V alloys with high aluminum content. The successful fulfillment of the proposal will expand the materials genome of stable III-V alloys and set design rules for high gain photodiodes. These "designer" APDs will have ten to twenty times lower noise in the critical telecommunications spectrum of wavelengths from three to five microns and be capable of single photon detection. Investigators will incorporate results into upcoming courses and books. They will also recruit students and teachers from underrepresented groups through a variety of programs and fellowships. Results will be presented at conferences and meetings with industry and government members through affiliated cooperative research centers. They will also be incorporated into demonstrations at annual Montessori events for children.Technical:The proposal will lead to the fundamental study of band formation and orbital chemistry in III-V alloys, towards controlling carrier ionization coefficients, excess noise and overall optoelectronic device design and noise reduction of Avalanche Photo Diodes (APDs). The proposal will involve the development of multi-scale computational models for electronic and optical transport of III-V alloy APDs and creation of design rules for low noise APDs with high gain. Experiments will focus on fabrication and characterization of digital and random III-V APDs, with varying material composition, orientation, temperature, periodicity, and roughness profile, and measurements of their electronic and optical properties to confirm predictions from the theoretical study and isolate the effect of competing mechanisms. Armed with these results, a Separate Absorption Charge Multiplication (SACM) APD will be fabricated to combine the different alloying needs for absorption vs multiplication, as well as high-speed Modified Uni-Traveling Carrier (MUTC) photodiodes to explore carrier saturation velocity. The ultimate goal will be to show operation at 25 and 50 Gigabit per second, enabling high performance 100 and 400 Gigabits per second coarse Wavelet Division Multiplexing Ethernet. Improving the performance of APDs for photon detection will open up their use in a wide range of commercial, military and research applications.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.