Two-color quantum-well infrared photodetectors ~QWIPs! that are based on electron transfer between coupled QWs suffer from the presence of the shorter wavelength peak at all bias voltages. We investigate this problem in such detectors with 50 or 200 Å AlGaAs barriers between the QW pair. We deduce the absorption coefficient a and photoconductive gain g of the detectors with 50 Å barriers using ...

Spin dephasing via the spin-orbit interaction (SOI) is a major mechanism limiting the electron spin lifetime in III-V zincblende quantum wells (QWs). The dephasing can be suppressed in GaAs(111) quantum wells by applying an electric field. The suppression has been attributed to the compensation of the intrinsic SOI associated with the bulk inversion asymmetry of the GaAs lattice by a structural...

Photocurrent oscillations, observed at low temperatures in lattice-matched Ga1-xInxNyAs1-y/GaAs multiple quantum well (MQW) p-i-n samples, are investigated as a function of applied bias and excitation wavelength and are modelled with the aid of semiconductor simulation software. The oscillations appear only at low temperatures and have the highest amplitude when the optical excitation energy is...

Temperature and carrier density-dependent spin dynamics for GaAs/AlGaAs quantum wells (QWs) with different structural symmetries have been studied by using time-resolved Kerr rotation technique. The spin relaxation time is measured to be much longer for the symmetrically designed GaAs QW comparing with the asymmetrical one, indicating the strong influence of Rashba spin-orbit coupling on spin r...

The low temperature photoluminescence under bias (PLb) and the photoconductivity (PC) of a p-i-n GaInNAs/GaAs multiple quantum well sample have been investigated. Under optical excitation with photons of energy greater than the GaAs bandgap, PC and PLb results show a number of step-like increases when the sample is reverse biased. The nature of these steps, which depends upon the temperature, e...

A theory of the transient spectroscopy of quantum well ~QW! structures under a large applied bias is presented. An analytical model of the initial part of the transient current is proposed. The time constant of the transient current depends not only on the emission rate from the QWs, as is usually assumed, but also on the subsequent carrier transport across QWs. Numerical simulation was used to...

We have investigated atomic intermixing in InxGa1−xAs/InP quantum well (QW) structures induced by proton irradiation using photoluminescence (PL) and time-resolved photoluminescence. Photoluminescence results revealed that energy shift was systematically decreased as irradiation temperature was increased, followed by a broadening of the PL linewidth and reduction of the PL intensity. Time-resol...

Using selective area epitaxy to produce three-dimensional GaN structures, two different concepts for laser diodes (LDs) with semipolar quantum wells (QWs) are developed, each having distinct advantages and disadvantages. The first approach utilizes a stripe with triangular cross-section not only to grow semipolar quantum wells on, but also as waveguide and resonator cavity. Based on simulations...

Spin-orbit interaction (SOI) in low-dimensional systems results in the fascinating property of spin-momentum locking. In a Rashba system the inversion symmetry normal to the plane of a two-dimensional (2D) electron gas is broken, generating a Fermi surface spin texture reminiscent of spin vortices of different radii which can be exploited in spin-based devices. Crucial for any application is th...

Fine structure related to different types of atomic arrangements (short-range order, phase separation and quantum dots) was observed in high-spatial-resolution low-temperature photoluminescence (PL) spectra of GaAsInN, GaAsSbN and GaAsInSbN quantum wells (QWs) containing ∼1.5% N and emitting at 1.2–1.3 μm. Using photoreflectance and temperature-dependent PL spectroscopy, we measured the activat...