Topic
Quantum well
About: Quantum well is a research topic. Over the lifetime, 44627 publications have been published within this topic receiving 674023 citations. The topic is also known as: QW & quantum potential well.
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TL;DR: It is reported that, counterintuitive to classical quantum-confined systems where photogenerated electrons and holes are strongly bound by Coulomb interactions or excitons, the photophysics of thin films made of Ruddlesden-Popper perovskites with a thickness exceeding two perovkite-crystal units is dominated by lower-energy states associated with the local intrinsic electronic structure of the edges of the perovSKite layers.
Abstract: Understanding and controlling charge and energy flow in state-of-the-art semiconductor quantum wells has enabled high-efficiency optoelectronic devices. Two-dimensional (2D) Ruddlesden-Popper perovskites are solution-processed quantum wells wherein the band gap can be tuned by varying the perovskite-layer thickness, which modulates the effective electron-hole confinement. We report that, counterintuitive to classical quantum-confined systems where photogenerated electrons and holes are strongly bound by Coulomb interactions or excitons, the photophysics of thin films made of Ruddlesden-Popper perovskites with a thickness exceeding two perovskite-crystal units (>1.3 nanometers) is dominated by lower-energy states associated with the local intrinsic electronic structure of the edges of the perovskite layers. These states provide a direct pathway for dissociating excitons into longer-lived free carriers that substantially improve the performance of optoelectronic devices.
798 citations
TL;DR: In this paper, a two-dimensional electron gas (2DEG) in a quantum well or inversion layer, unlike an ordinary grounded metallic plane, does not completely screen an applied transverse electric field, but partial penetration of an external field through a highly conducting 2DEG allows the implementation of several novel high-speed devices, including a threeterminal resonant tunneling transistor and a gate-controlled thermionic emission transistor.
Abstract: Two‐dimensional electron gas (2DEG) in a quantum well or inversion layer, unlike an ordinary grounded metallic plane, does not completely screen an applied transverse electric field. Owing to its Fermi degeneracy energy, a 2DEG manifests itself as a capacitor in series, whose capacitance per unit area equals CQ=me2/πℏ2, where m is the effective electron mass in the direction transverse to the quantum well. Partial penetration of an external field through a highly conducting 2DEG allows the implementation of several novel high‐speed devices, including a three‐terminal resonant‐tunneling transistor and a gate‐controlled thermionic emission transistor.
793 citations
TL;DR: In this paper, the experimental and theoretical investigations of the linear and nonlinear optical properties of semiconductor quantum well structures, including the effects of electrostatic fields, extrinsic carriers and real or virtual photocarriers, are reviewed.
Abstract: In this article we review the experimental and theoretical investigations of the linear and nonlinear optical properties of semiconductor quantum well structures, including the effects of electrostatic fields, extrinsic carriers and real or virtual photocarriers.
791 citations
TL;DR: This analysis shows strong evidence for the existence of helical edge modes proposed by Liu et al, which persist in spite of sizable bulk conduction and show only a weak magnetic field dependence.
Abstract: We present an experimental study of low temperature electronic transport in the hybridization gap of inverted InAs/GaSb composite quantum wells. An electrostatic gate is used to push the Fermi level into the gap regime, where the conductance as a function of sample length and width is measured. Our analysis shows strong evidence for the existence of helical edge modes proposed by Liu et al [Phys. Rev. Lett. 100, 236601 (2008)]. Edge modes persist in spite of sizable bulk conduction and show only a weak magnetic field dependence-a direct consequence of a gap opening away from the zone center.
790 citations
TL;DR: A variational calculation of hydrogenic impurity states in a quantum well has been performed in this article, where the binding energy of donor (acceptor) levels is calculated as a function of layer thickness and of the impurity position.
Abstract: A variational calculation of hydrogenic impurity states in a quantum well has been performed. The binding energy of donor (acceptor) levels is calculated as a function of layer thickness and of the impurity position. It is found that the ground impurity state degeneracy with respect to the impurity position is lifted, leading to the formation of some sort of an "impurity band." The density of states of this impurity band exhibits one or two peaks energetically located at the "band" extrema. This one-dimensional feature can be evidenced in the optical absorption associated with valence subband\ensuremath{\rightarrow}donor transitions, whereas acceptor\ensuremath{\rightarrow}conduction processes are almost featureless. In the case of conduction\ensuremath{\rightarrow}acceptor luminescence a smooth curve is obtained for degenerate electronic distribution, whereas nondegenerate electron\ensuremath{\rightarrow}trapped hole recombination spectra should again exhibit a double peak.
778 citations