Quasi-2D perovskites have shown great potential in achieving solution-processed electrically pumped laser diodes due to their multiple-quantum-well structure, which induces a carrier cascade process that can significantly enhance population inversion. However, continuous-wave (CW) optically pumped lasing has yet to be achieved with near-infrared (NIR) quasi-2D perovskites due to the challenges in obtaining high-quality quasi-2D films with suitable phase distribution and morphology. This study regulates the crystallization of a NIR quasi-2D perovskite ((NMA)2FAn−1PbnI3n+1) using an 18-crown-6 additive, resulting in a compact and smooth film with a largely improved carrier cascade efficiency. The amplified spontaneous emission threshold of the film is reduced from 47.2 to 35.9 µJ cm−2. Furthermore, by combining the film with a high-quality distributed feedback grating, this study successfully realizes a CW NIR laser of 809 nm at 110 K, with a high Q-factor of 4794 and a low threshold of 911.6 W cm−2. These findings provide an important foundation for achieving electrically pumped laser diodes based on the unique quasi-2D perovskites. 相似文献
Managing trap states and understanding their role in ultrafast charge‐carrier dynamics, particularly at surface and interfaces, remains a major bottleneck preventing further advancements and commercial exploitation of nanowire (NW)‐based devices. A key challenge is to selectively map such ultrafast dynamical processes on the surfaces of NWs, a capability so far out of reach of time‐resolved laser techniques. Selective mapping of surface dynamics in real space and time can only be achieved by applying four‐dimensional scanning ultrafast electron microscopy (4D S‐UEM). Charge carrier dynamics are spatially and temporally visualized on the surface of InGaN NW arrays before and after surface passivation with octadecylthiol (ODT). The time‐resolved secondary electron images clearly demonstrate that carrier recombination on the NW surface is significantly slowed down after ODT treatment. This observation is fully supported by enhancement of the performance of the light emitting device. Direct observation of surface dynamics provides a profound understanding of the photophysical mechanisms on materials' surfaces and enables the formulation of effective surface trap state management strategies for the next generation of high‐performance NW‐based optoelectronic devices. 相似文献
With the wide application of cloud computing, the scale of cloud data center network is growing. The virtual machine (VM) live migration technology is becoming more crucial in cloud data centers for the purpose of load balance, and efficient utilization of resources. The lightweight virtualization technique has made virtual machines more portable, efficient and easier to management. Different from virtual machines, containers bring more lightweight, more flexible and more intensive service capabilities to the cloud. Researches on container migration is still in its infancy, especially live migration is still very immature. In this paper, we present the locality live migration model where we take into account the distance, available bandwidth and costs between containers. Furthermore, we conduct comprehensive experiments on a cluster. Extensive simulation results show that the proposed method improves the utilization of resources of servers, and also improves the balance of all kinds of resources on the physical machine.