A. Ben Fredj

Energy-band structure and optical gain in strained InAs"N…/GaSb/InAs"N… quantum well lasers.

We present a theoretical study of band structure and optical gain spectra of dilute-N InAsN/GaSb/InAsN and the similar N-free InAs/GaSb/InAs laser structures, which have a “W” band alignment. Calculations are based on a 10×10 k⋅p model incorporating valence, conduction, and nitrogen-induced bands. The two laser diodes are designed to operate at 3.3 μm at room temperature. We find that the incorporation of a few percent of nitrogen in the laser active region improves optical gain performance, which leads to a peak gain value of approximately 1000 cm−1 for a typical injection carrier concentration of 1×1012 cm−2 and a carrier transparent density of 0.54×1018 cm−3.

Evidence of triplet–triplet interaction in crystalline sexithiophene

Abstract Optically detected magnetic resonance (ODMR) experiments are performed at room temperature on crystalline sexithiophene (6T) photoluminescence (PL). The observed spectra are interpreted in terms of microwave induced transitions between spin sublevels of triplet–triplet pairs states. These triplets are produced by intersystem crossing and their mutual annihilation which leads to delayed fluorescence (DF) is modulated by the high power microwave and enhance the PL process.

Role of recombination, dissociation, and competition between exciton-charge reactions in magnetoconductance of polymeric semiconductor device

Magnetoelectrical measurements were performed on a diode structure, based on an anthracene-containing poly(arylene-ethynylylene)-alt-poly(arylene-vinylene) denoted AnE-PVstat, to clarify the role of the recombination and dissociation of electron-hole (e-h) pairs in the magnetoconductance (MC). We report the observed MC under a weak magnetic field (<1 T) at room and low temperatures. Positive MC is observed and reaches up to 2% at a magnetic field of 450 mT at room temperature. It is found that with the increase of the voltage, the MC effect decreases. We also report the difference in MC between perpendicular (θ = 90°) and parallel (θ = 0°) alignment of magnetic field with respect to the current direction. The experimental data were analyzed in the context of the e-h pair model, based on the Stochastic Liouville Equation. To interpret the experimental results on magnetoconductance measurements, anisotropic hyperfine interaction has been introduced through an anisotropic hyperfine field. The dissociation ra...