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.

Two-dimensional arsenene oxide: A realistic large-gap quantum spin Hall insulator

Abstract: Searching for two-dimensional (2D) realistic materials that are able to realize room-temperature quantum spin Hall effects is currently a growing field. Here, through ab initio calculations, we identify arsenene oxide, AsO, as an excellent candidate, which demonstrates high stability, flexibility, and tunable spin-orbit coupling gaps. In contrast to known pristine or functionalized arsenene, the maximum nontrivial bandgap of AsO reaches 89 meV and can be further enhanced to 130 meV under biaxial strain. By sandwiching 2D AsO between boron nitride sheets, we propose a quantum well in which the band topology of AsO is preserved with a sizeable bandgap. Considering that AsO having fully oxidized surfaces are naturally stable against surface oxidization and degradation, this functionality provides a viable strategy for designing topological quantum devices operating at room temperature.

A room temperature continuous-wave nanolaser using colloidal quantum wells.

Abstract: Colloidal semiconductor nanocrystals have emerged as promising active materials for solution-processable optoelectronic and light-emitting devices. In particular, the development of nanocrystal lasers is currently experiencing rapid progress. However, these lasers require large pump powers, and realizing an efficient low-power nanocrystal laser has remained a difficult challenge. Here, we demonstrate a nanolaser using colloidal nanocrystals that exhibits a threshold input power of less than 1 μW, a very low threshold for any laser using colloidal emitters. We use CdSe/CdS core-shell nanoplatelets, which are efficient nanocrystal emitters with the electronic structure of quantum wells, coupled to a photonic-crystal nanobeam cavity that attains high coupling efficiencies. The device achieves stable continuous-wave lasing at room temperature, which is essential for many photonic and optoelectronic applications. Our results show that colloidal nanocrystals are suitable for compact and efficient optoelectronic devices based on versatile and inexpensive solution-processable materials. Colloidal nanocrystals are a promising material for easy-to-fabricate nanolasers, but suffer from high threshold powers. Here, the authors combine colloidal quantum wells with a photonic-crystal cavity into a stable, continuous-wave room-temperature nanolaser with a threshold below one microwatt

Tunable spin-splitting and spin-resolved ballistic transport in GaAs/AlGaAs two-dimensional holes

Abstract: We report quantitative experimental and theoretical results revealing the tunability of spin splitting in high-mobility two-dimensional GaAs hole systems, confined to either a square or a triangular quantum well, via the application of a surface-gate bias. The spin splitting depends on both the hole density and the symmetry of the confinement potential and is largest for the highest densities in asymmetric potentials. In the triangular well, when the spin splitting is sufficiently large, our measured commensurability oscillations, induced by a one-dimensional periodic potential, exhibit two frequencies providing clear evidence for spin-resolved ballistic transport.

Top-surface-emitting GaAs four-quantum-well lasers emitting at 0.85 mu m

Abstract: Room-temperature CW and pulsed lasing of top-surface-emitting, vertical-cavity, self-aligned, GaAs quantum-well lasers is achieved at ~845 nm. The active gain medium is four 100-A-thick GaAs quantum wells. The whole structure is grown by molecular beam epitaxy. Deep H+-ion implantation followed by annealing is used to control a vertical profile of resistivity for an efficient current injection at the active region. The threshold current is 2.2 mA for CW and pulsed operation using 10-jam diameter lasers. Differential quantum efficiency is about 20%. Minimum threshold current density per quantum well of 360 A/cm2 is obtained. Maximum CW output power better than 1.5 mW is obtained.

Ideal theory of quantum well solar cells

Abstract: An ideal model for quantum well solar cells is developed and is used to theoretically explore the dependence of terminal characteristics on the host cell and quantum well properties. The model, which explicitly treats carrier generation and recombination in the quantum wells, is described and compared with an analogous ideal model for bulk homojunction cells. Open‐circuit voltages, short‐circuit current densities, and conversion efficiencies are then calculated as functions of the well and barrier band gaps for ideal cells in the radiative limit, assuming air‐mass‐zero (AM0) solar illumination at a cell temperature of 300 K. Qualitative trends in these characteristics and regimes of operation are identified, the effects of non‐radiative recombination are explored, and idealized approximations used in the model are assessed. Finally, published experimental data for quantum well solar cells are surveyed and discussed, and are found to exhibit strong qualitative consistencies with predictions from the ideal ...