Abstract
We investigate the emission from confined excitons in the structure of a single-monolayer-thick quasi-two-dimensional (quasi-2D) InxGa1−xN layer inserted in GaN matrix. This quasi-2D InGaN layer was successfully achieved by molecular beam epitaxy (MBE), and an excellent in-plane uniformity in this layer was confirmed by cathodoluminescence mapping study. The carrier dynamics have also been investigated by time-resolved and excitation-power-dependent photoluminescence, proving that the recombination occurs via confined excitons within the ultrathin quasi-2D InGaN layer even at high temperature up to ~220 K due to the enhanced exciton binding energy. This work indicates that such structure affords an interesting opportunity for developing high-performance photonic devices.
Highlights
In recent years, a series of two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides and black phosphorus, have attracted much research attention due to their remarkable physical properties and novel applications[1]
The sample was grown by plasma-assisted molecular beam epitaxy (MBE, SVTA) and the growth was in-situ monitored by reflection high-energy electron diffraction (RHEED)
A 4.5 μm-thick GaN layer on c-plane sapphire was used as the template
Summary
A series of two-dimensional (2D) materials, such as graphene, transition metal dichalcogenides and black phosphorus, have attracted much research attention due to their remarkable physical properties and novel applications[1]. The optoelectronic devices based on these materials are mostly limited by several difficulties, including fabrication of large-area high-quality materials, making high efficient doping, subsequent Ohmic contact, and so on[2]. This encourages people to search for new approaches and materials which should show novel 2D nature in ultrathin layers but are suitable for bulk planar technology. Fabrication of high quality thick InGaN films on GaN suffers from two obstacles, i.e. high density threading dislocations and phase separation with In-rich clusters The former one arises from large thermal/lattice mismatch between InN and GaN template, while the latter one results from very low InN solubility in GaN at common growth temperature[10,11]. (PL), confirming that the PL emission does originate from the recombination of confined excitons for temperatures up to ~220 K
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