OP: Towards Electrically Pumped Perovskite Quantum Dot Lasers

具有微型元件尺寸和高集成密度的光子集成电路已被视为可能在现代计算和通信系统中提供突破性进步的技术，因为它旨在实现可以克服诸如速度、带宽和功耗等几个瓶颈电子技术遇到的VLSI的光学模拟。光子集成电路中的关键组件包括激光器、波导、调制器和光电探测器，这些组件可以在低成本的Si平台上光刻定义和制造，以实现最终的系统兼容性。其中，由于激光增益材料和Si之间的不兼容制造工艺，激光器与Si集成是最具挑战性的。除了计算和光纤通信，激光器的特点是易于集成在硅可以找到广阔的应用范围，在自由空间通信，投影显示，照明，光谱，传感，生物医学等波长范围从紫外线，可见光到红外线光谱都是理想的，这取决于应用。尽管已经追求基于芯片级键合和在体硅、纳米线或量子点（QD）形式上的III-V外延生长的异质光电子学，但是制造工艺被详细阐述，这可能使成本保持高。有机材料等溶液处理材料提供了一条有前途的途径来克服这一挑战，因为它们可以在各种各样的基板上制造，有机LED已经实现了令人印象深刻的性能，现在已经可以商业化。但这种材料还不能实现激光操作，主要是由于低电荷迁移率。近年来，杂化有机-无机卤化物钙钛矿材料已经成为光子材料中非常有前途的新人。这些材料表现出高电荷迁移率，尖锐的光学吸收边和高吸收系数相媲美的GaAs，以及一个不寻常的缺陷容限。虽然已经实现了在各种谐振腔形式的钙钛矿材料中的激光发射，但是具有适合于光子集成电路的设计谐振腔的钙钛矿激光器尚未被证明。此外，钙钛矿材料的稳定性仍然是该领域的主要关注点，并且电泵浦仍然是钙钛矿激光器的具有挑战性的首要目标。该研究的目的是改善和优化实现钙钛矿激光器电泵浦的关键参数，并评估电流注入下钙钛矿激光器工作的可行性。我们将研究钙钛矿材料的特性，以提高电荷迁移率和材料稳定性。将探索电子和空穴传输层的工程以及器件设计，以进一步提高整体器件的稳定性。一个垂直腔激光器将被设计和制造，和优化的谐振腔的基础上，PI的光泵钙钛矿QD垂直腔激光器的工作将被追求。一个波导分布反馈（DFB）激光器，可以光刻定义和完全兼容的硅光子集成电路制造也将进行探索。这些边发射波导激光器由于较长的增益长度和高度受限的光学模式而有望实现较低的激射阈值。将采用具有温度控制的脉冲电流注入来评估电泵浦的可行性。通过所提出的研究，电泵浦钙钛矿激光器的关键问题将通过同时研究器件设计和制造的几个方面来探索和解决，包括材料加工，电界面，光学结构和谐振腔。该研究成果将为实现电泵浦钙钛矿激光器提供必要的知识，为硅芯片上集成激光器提供了一条有前途的途径。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Photonic integrated circuits with miniature component sizes and high integration density have been regarded as the technology that can potentially provide breakthrough advancement in modern computing and communication systems, as it aims to achieve an optical analogy of VLSI that can overcome several bottleneck electronic technologies encounter such as speed, bandwidth, and power consumption. Key components in photonic integrated circuits include lasers, waveguides, modulators, and photodetectors that can be lithographically defined and fabricated on low-cost Si platforms to achieve ultimate system compatibilities. Among these, lasers have been the most challenging to integrate with Si due to the incompatible fabrication processes between laser gain materials and Si. In addition to computing and optical fiber communications, lasers that feature facile integration on Si can find vast application scopes in free-space communications, projection displays, lighting, spectroscopy, sensing, biomedicine, etc. Wavelength spectra ranging from UV, visible to IR are all desirable depending on the applications. Although heterogeneous optoelectronics based on chip-level bonding and III-V epitaxial growth on Si in bulk, nanowire or quantum dot (QD) forms have been pursued, the fabrication processes are elaborated which is likely to keep the cost high. Solution-processed materials such as organic materials offer a promising route to overcome this challenge as they can be fabricated on a wide variety of substrates, and organic LEDs have achieved impressive performance and are commercially available now. But the material has not been able to achieve laser operations chiefly due to low charge mobility. In recent years, hybrid organic-inorganic halide perovskite materials have emerged as a highly promising newcomer among photonic materials. These materials exhibit high charge mobility, sharp optical absorption edges and high absorption coefficients comparable to GaAs, as well as an unusual defect tolerance. Although lasing in perovskite materials in various resonant-cavity forms have been achieved, perovskite lasers with designed resonant cavities suitable for photonic integrated circuits have not been demonstrated. Furthermore, stability of the perovskite materials is still a main concern in this field, and electrical pumping remains a challenging, overarching goal for perovskite lasers. The objective of the proposed research is to improve and optimize key parameters for achieving electrical pumping in perovskite lasers, and to assess the feasibility of perovskite laser operation under current injection. We will investigate perovskite material properties to improve the charge mobility and material stability. Engineering of the electron and hole transport layers, as well as the device design, will be explored to further enhance the overall device stability. A vertical cavity laser will be designed and fabricated, and optimization of the resonant cavity based on the PI's prior work on optically pumped perovskite QD vertical cavity lasers will be pursued. A waveguide distributed feedback (DFB) laser that can be lithographically defined and fully compatible with Si photonic integrated circuit fabrication will also be explored. These edge-emitting waveguide lasers are expected to achieve lower lasing threshold due to longer gain length and highly confined optical modes. Pulsed current injection with temperature control will be employed to assess the feasibility of electrical pumping. Through the proposed research, key issues for electrically pumped perovskite lasers will be probed and addressed by investigating several aspects of device design and fabrication simultaneously, including material processing, electrical interfaces, optical structures and resonant cavities. The results will contribute to necessary knowledge for realizing electrically pumped perovskite lasers, which provide a promising route to integrated lasers on Si chips.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.