The applications of self-assembled InAs/GaAs quantum dots (QDs) for lasers and single photon sources strongly rely on their density and quality. Establishing the process parameters in molecular beam epitaxy (MBE) for a specific density of QDs is a multidimensional optimization challenge, usually addressed through time-consuming and iterative trial-and-error. Here, we report a real-time feedback control method to realize the growth of QDs with arbitrary density, which is fully automated and intelligent. We develop a machine learning (ML) model named 3D ResNet 50 trained using reflection high-energy electron diffraction (RHEED) videos as input instead of static images and providing real-time feedback on surface morphologies for process control. As a result, we demonstrate that ML from previous growth could predict the post-growth density of QDs, by successfully tuning the QD densities in near-real time from 1.5 × 10¹⁰cm⁻² down to 3.8 × 10⁸cm⁻² or up to 1.4 × 10¹¹cm⁻². Compared to traditional methods, our approach can dramatically expedite the optimization process and improve the reproducibility of MBE. The concepts and methodologies proved feasible in this work are promising to be applied to a variety of material growth processes, which will revolutionize semiconductor manufacturing for optoelectronic and microelectronic industries.

InGaN NWs were grown on a metallic Ti/Si template that improved the photoelectrochemical performance and stability, and reduced the interfacial transfer resistance.

The recent study of a wide range of layered transition metal dichalcogenides (TMDCs) has created a new era for device design and applications. In particular, the concept of van der Waals epitaxy (vdWE) utilizing layered TMDCs has the potential to broaden the family of epitaxial growth techniques beyond the conventional methods. We report herein, for the first time, the monolithic high-power, droop-free, and wavelength tunable InGaN/GaN nanowire light-emitting diodes (NW-LEDs) on large-area MoS₂ layers formed by sulfurizing entire Mo substrates. MoS₂ serves as both a buffer layer for high-quality GaN nanowires growth and a sacrificial layer for epitaxy lift-off. The LEDs obtained on nitridated MoS₂ via quasi vdWE show a low turn-on voltage of ∼2 V and light output power up to 1.5 mW emitting beyond the “green gap”, without an efficiency droop up to the current injection of 1 A (400 A cm⁻²), by virtue of high thermal and electrical conductivities of the metal substrates. The discovery of the nitride/layered TMDCs/metal heterostructure platform also ushers in the unparalleled opportunities of simultaneous high-quality nitrides growth for high-performance devices, ultralow-profile optoelectronics, energy harvesting, as well as substrate reusability for practical applications.

Quantum emitters are a key component in photonic quantum technologies. Enhancing single-photon emission by engineering their photonic environment is essential for improving overall efficiency in quantum information processing. However, this enhancement is often limited by the need for ultraprecise emitter placement within conventional photonic cavities. Inspired by the fascinating physics of moiré pattern, we propose a multilayer moiré photonic crystal with a robust isolated flatband. Theoretical analysis reveals that, with nearly infinite photonic density of states, the moiré cavity simultaneously has a high Purcell factor and large tolerance over the emitter’s position, breaking the constraints of conventional cavities. We then experimentally demonstrate various cavity quantum electrodynamic phenomena with a quantum dot in moiré cavity. A large tuning range (up to 40-fold) of quantum dot’s radiative lifetime is achieved through strong Purcell enhancement and inhibition effects. Our findings open the door for moiré flatband cavity–enhanced quantum light sources and quantum nodes for the quantum internet.