Observation of Emission Enhancement Caused by Symmetric Carrier Depletion in III–V Nanomembrane Heterostructures

Abstract

Semiconductor nanomembranes are promising systems for many applications, since the band structure of a given material can be tailored to achieve specific configurations, which are not feasible by conventional growth procedures on rigid substrates. Here we show that optically active III–V membranes containing InAs quantum dots exhibit a pronounced photoluminescence enhancement with respect to equivalent systems grown on top of flat substrates. The effect is explained by the formation of carrier depletion regions symmetrically located with respect to the optically active layer. This leads to the filling of excited states of the quantum dots and the overall spectra are enhanced at higher energies. Changes on the strain field that are expected to lead to a red-shift of the quantum dot emission play a reduced role in the final emission spectra in comparison with the depletion effects. These effects can be considered as another degree of freedom and a key ingredient for band engineering of extremely thin semiconductor membranes.

Pseudo-magnetic-field and effective spin-orbit interaction for a spin-1/2 particle confined to a curved surface

“…From Eq. ( 21), the relation between the determinants G and g can be calculated as G = f 2 g, where f = 1 + Tr(α ab )q 3 + det(α ab )q 2 3 named as the rescaled factor. Under the rescaled transformation, an introduced new wave function ψ and the Hamiltonian in Eq.…”

“…During the last decade, inspired by the technical progress in the fabrication of low-dimensional nanostructures [1][2][3][4][5][6], there have been many theoretical and experimental researches on the dynamics in low-dimensional curved spaces, involving condensed matter [7][8][9][10], optics [11][12][13], and magnetism [14,15]. Due to the appearance of curvature, physical quantities of the particle in the low-dimensional curved space may lose some symmetries associated with space coordinates, such as translational symmetry and rotational symmetry, manifesting novel and abundant properties different from flat cases.…”

Polycrystalline Au Nanomembrane as a Tool for Two-Tone Micro/Nanolithography

“…Nanomembranes are thin films with nanoscale thickness. They have attracted great interest from various fields owing to their mechanical, − electrical, − and optical properties. ,− For example, Si nanomembranes have been used as microelectromechanical system (MEMS) sensors, − ion channel filters, ,− and optical switches. ,,− To broaden their applications to biotechnological fields, organic nanomembranes, including graphene, have been developed. In this application, the use of biocompatible materials is important; thus, nanomembranes of hydrogels and nontoxic polymers have been reported.…”

“…Metals are also good materials with which to enhance the functionality of nanomembranes due to their high conductivity, magnetic properties, and potential plasmonic effects. In particular, roll-up fabrication of metal nanomembranes using a sacrificial etching layer has been developed by Schmidt et al, ,,,− and can be used for MEMS sensors, ,, micromotors, , and supercapacitors . Further, atomically thin iron nanomembranes suspended in graphene have recently been synthesized to potentially be used as graphene-based functional magnetic materials …”

Effective dynamics for a spin-1/2 particle constrained to a space curve in an electric and magnetic field

“…In addition to astronomical surveys, it seems unlikely that we can investigate large curvature effect in conventional laboratories. While during the last decades, the technique in synthesis of nanostructures has made great progress [1][2][3][4], which brings large space curvature to the lab. These nanostructures with curved geometries provide a platform for studies on the dynamics in low-dimensional curved spaces, involving condensed matter [5][6][7], optics [8,9] and magnetism [10,11].…”