An investigation of exciton behavior in type-II self-assembled GaSb/GaAs quantum dots

Abstract

We report the investigation of exciton dynamics in type-II self-assembled GaSb/GaAs quantum dots. The GaSb/GaAs quantum dots (QDs) were grown using a modified liquid phase epitaxy technique. Statistical size distributions of the uncapped QDs were investigated experimentally by field-emission scanning electron microscopy (SEM) and atomic force microscopy (AFM), and theoretically by an eight-band k · p calculation, which demonstrated a dissolution effect. Furthermore, the low-temperature luminescence spectra of type-II GaSb/GaAs QDs with a thick capping layer exhibit well-resolved emission bands and LO-phonon-assisted transitions in the GaSb wetting layer. However, the luminescence lines quench at temperatures above 250 K, which is attributed to the weak quantum confinement of electrons participating in indirect exciton recombination. It was demonstrated that the room temperature stability of the excitons in type-II GaSb/GaAs QDs could be achieved by growing thin a capping layer, which provides strong quantum confinement in the conduction band and enhances the electron-hole Coulomb interaction, stabilizing the excitons.

Nano Ball‐Milling Using Titania Nanoparticles to Anchor Cesium Lead Bromine Nanocrystals and Energy Transfer Characteristics in TiO2@CsPbBr3 Architecture

“…Meanwhile, due to different contour of CsPbBr 3 NCs in the work, the surface area of spherical NCs in the TiO 2 @CsPbBr 3 is πD 2 , where D is the diameter of the sphere. However, the surface area of pristine cubic CsPbBr 3 NCs is 6a 2 , where a is the length of a side of cubic. Since the average diameter of CsPbBr 3 in the TiO 2 @CsPbBr 3 architecture is smaller than that of the pristine CsPbBr 3 NCs.…”

“…In past few years, all-inorganic lead halide perovskite nanocrystals (NCs) have gained extensively attention due to their relatively facile synthetic methods and distinct luminescence characteristics compared to other NCs and quantum dots. [1][2][3][4][5] As an outstanding candidate of photoluminescent materials, the characters of carrier transport in CsPbX 3 are modulated by the interfacial electronic states, and band structure between the heterogeneous crystalline materials and CsPbX 3 NCs, which can further tune and improve their photoluminescence characteristics. [6][7][8][9][10] For example, CsPbX 3 heterojunctions with Au, Ag, MoS 2 , PbS , and Bi 2 Se 3 have been studied in order to improve their stability and luminous performance.…”

Insight into the Origins of Figures of Merit and Design Strategies for Organic/Inorganic Lead‐Halide Perovskite Solar Cells

“…Sometimes, the existence of gap states can promote carrier transport and transfer by the interfacial dipole effect to overcome unfavorable energy‐level alignment [108a,156] . Furthermore, energy‐level alignments are also subject to an upshift in the vacuum level due to the formation of interfacial dipoles, quantum size effects, or band bending [111b,154a,157] …”

Stoichiometry-Modulated Resonant Raman Spectroscopy of WS2(1–x)Se2x-Alloyed Monolayer Nanosheets

“…; X = S, Se, Te) − have attracted enormous interests in diverse applications such as valleytronics, photosensors, nanocavity lasers, light-emitting diode (LED), , etc. Inspired by the band gap tailoring effect in alloyed ternary semiconductors, − alloying two MX 2 components is expected to form a ternary TMD semiconductor with a tunable band gap, enabling the manufacturing of an optoelectronic device with tunable spectral response possibly matching the incident optical spectrum. Meanwhile, the excitonic energies, carrier type, and concentration can be further modulated in a wide range.…”