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.

Large optical gain AlGaN-delta-GaN quantum wells laser active regions in mid- and deep-ultraviolet spectral regimes

Abstract: The gain characteristics of high Al-content AlGaN-delta-GaN quantum wells (QWs) are investigated for mid- and deep-ultraviolet (UV) lasers. The insertion of an ultrathin GaN layer in high Al-content AlGaN QWs leads to valence subbands rearrangement, which in turn results in large optical gain for mid- and deep-UV lasers.

Growth of high-quality ZnMgO epilayers and ZnO/ZnMgO quantum well structures by radical-source molecular-beam epitaxy on sapphire

Abstract: We report on a specific growth procedure combining low-temperature growth of ZnMgO and postgrowth annealing at intermediate temperatures. Despite the large lattice misfit induced by the sapphire substrate, layer-by-layer growth is accomplished up to the phase-separation limit found at a c-lattice constant of 0.5136nm and Mg mole fraction of 0.40. The procedure allows us to grow quantum wells with atomically smooth interfaces in a wide range of structural designs exhibiting prominent emission features up to room temperature.

Modeling the spectral response of the quantum well solar cell

Abstract: The quantum well solar cell is an alternative to more conventional multiband gap approaches to higher cell efficiency. Preliminary studies have shown that the insertion of a series of quantum wells into the depletion region of a GaAs/AlxGa1−xAs p‐i‐n solar cell can significantly enhance the cell’s short‐circuit current. We present here a model for the spectral response of GaAs and AlxGa1−xAs p‐n and p‐i‐n solar cells, with and without quantum wells, based on a standard solution of the minority‐carrier equations. Particular emphasis is placed on modeling the absorption coefficient of the AlxGa1−xAs and of the quantum wells. We find that our model can accurately predict the spectral response of a wide variety of cells: both conventional p‐n junctions in GaAs and AlxGa1−xAs, and various geometries of quantum well solar cell in AlxGa1−xAs/GaAs (x∼0.3). We discuss the strengths and weaknesses of the model and its underlying assumptions, and conclude by using the model to design p‐i‐n quantum well solar cells w...

Two‐dimensional phase‐locked arrays of vertical‐cavity semiconductor lasers by mirror reflectivity modulation

Abstract: Coupling of two‐dimensional (2D) vertical‐cavity surface‐emitting lasers (VCSELs) to give a coherent supermode is described. The top metal layer of a stained‐layer InGaAs quantum well VCSEL structure was patterned laterally by depositing various metals with different optical reflectivities. This lateral reflectivity patterning defined a 2D laser array sharing the same ‘‘supercavity’’. It is shown that these 2D arrays oscillate in a stable single, coherent 2D supermode. This was achieved with a simple planar process and without significant deterioration of threshold current and efficiency relative to an equivalent broad‐area VCSEL.

Quantum-well resonant tunneling bipolar transistor operating at room temperature

Abstract: The first resonant tunneling bipolar transistor (RBT) is reported. The AlGaAs/GaAs wide-gap emitter device, grown by molecular beam epitaxy (MBE), contains a GaAs quantum well and two AlAs barriers between the emitter and the collector. In the common emitter configuration, when the base current exceeds a threshold value, a large drop in the collector current (corresponding to a quenching of the current gain β) is observed at room temperature, along with a pronounced negative conductance as a function of the collector-emitter voltage. These striking characteristics are caused by the quenching of resonant tunneling through the double barrier as the conduction band edge in the emitter is raised above the bottom of the first quantized subband of the well. Single-frequency oscillations are observed at 300 K. The inherent negative transconductance of these new functional devices is extremely valuable for many logic and signal processing applications.