Deep-ultraviolet integrated photonic and optoelectronic devices:A prospect of the hybridization of group Ⅲ–nitrides, Ⅲ–oxides,and two-dimensional materials

Progress in the design and fabrication of ultraviolet and deep-ultraviolet groupⅢ–nitride optoelectronic devices,based on aluminum gallium nitride and boron nitride and their alloys,and the heterogeneous integration with two-dimensional and oxide-based materials is reviewed.We emphasize wide-bandgap nitride compound semiconductors(i.e.,(B,Al,Ga)N)as the deep-ultraviolet materials of interest,and two-dimensional materials,namely graphene,two-dimensional boron nitride,and two-dimensional transition metal dichalcogenides,along with gallium oxide,as the hybrid integrated materials.We examine their crystallographic properties and elaborate on the challenges that hinder the realization of efficient and reliable ultraviolet and deep-ultraviolet devices.In this article we provide an overview of aluminum nitride,sapphire,and gallium oxide as platforms for deep-ultraviolet optoelectronic devices,in which we criticize the status of sapphire as a platform for efficient deep-ultraviolet devices and detail advancements in device growth and fabrication on aluminum nitride and gallium oxide substrates.A critical review of the current status of deep-ultraviolet light emission and detection materials and devices is provided.

Large-scale and high-quality III-nitride membranes through microcavity-assisted crack propagation by engineering tensile-stressed Ni layers

Epitaxially grown III-nitride alloys are tightly bonded materials with mixed covalent-ionic bonds.This tight bonding presents tremendous challenges in developing III-nitride membranes,even though semiconductor membranes can provide numerous advantages by removing thick,inflexible,and costly substrates.Herein,cavities with various sizes were introduced by overgrowing target layers,such as undoped GaN and green LEDs,on nanoporous templates prepared by electrochemical etching of n-type GaN.The large primary interfacial toughness was effectively reduced according to the design of the cavity density,and the overgrown target layers were then conveniently exfoliated by engineering tensile-stressed Ni layers.The resulting III-nitride membranes maintained high crystal quality even after exfoliation due to the use of GaN-based nanoporous templates with the same lattice constant.The microcavity-assisted crack propagation process developed for the current III-nitride membranes forms a universal process for developing various kinds of large-scale and high-quality semiconductor membranes.