Studies of Diluted Magnetic Semiconductor Sn1−x−y−zGexMnyGdzTeSn_{1-x-y-z}Ge_{x}Mn_{y}Gd_{z}Te

Magnetization, anomalous Hall effect, thermoelectric power, magnetoresistance, and resistivity of $Sn_{1-x-y-z}Ge_{x}Mn_{y}Gd_{z}Te$ (x = 0.039÷0.597, y = 0.077÷0.125, z = 0.0014÷0.028) mixed crystals were studied over the temperature range 4.2-300 K. The ferromagnetic order with Curie temperature 18-24 K was revealed

Ultra-fast charge carrier dynamics across the spectrum of an optical gain media based on InAs/AlGaInAs/InP quantum dots

The charge carrier dynamics of improved InP-based InAs/AlGaInAs quantum dot (QD) semiconductor optical amplifiers are examined employing the multi-wavelength ultrafast pump-probe measurement technique. The transient transmission response of the continuous wave probe shows interesting dynamical processes during the initial 2-3 ps after the pump pulse, when carriers originating from two photon absorption contribute the least to the recovery. The effects of optical excitations and electrical bias levels on the recovery dynamics of the gain in energetically different QDs are quantified and discussed. The experimental observations are validated qualitatively using a comprehensive finite-difference time-domain model by recording the time evolution of the charge carriers in the QDs ensemble following the pulse

Ultraviolet Detectors Based on ZnO:N Thin Films with Different Contact Structures

Al/ZnO:N/Al and Ni/ZnO:N/Al diode photodetectors fabricated by dc magnetron sputtering of ZnO:N films on p-Si substrates are studied. The photocurrent-to-dark current ratio equal to 250 at λ= 390 nm and the time constant of photoresponse about 10 μs for Al/ZnO:N/Al structures with 4 μm interdigital spacing was achieved. The Ni/ZnO:N/Al diode structure has the rectification ratio ≈10² at bias 1 V, the maximal responsivity about 0.1 A/W is observed at 365 nm, and the measured time constant of photoresponse is about 100 ns

Ferromagnetism of Narrow-Gap Ge1−x−ySnxMnyTeGe_{1-x-y}Sn_xMn_yTe and Layered In1−xMnxSeIn_{1-x}Mn_xSe Semiconductors

Magnetic susceptibility, Hall effect and resistivity of narrow-gap $Ge_{1-x-y}Sn_xMn_yTe$ single crystals (x = 0.083÷0.115; y = 0.025÷0.124) were investigated in the temperature range 4.2-300 K revealing a ferromagnetic ordering at $T_C$ ≈ 50 K. Temperature dependence of magnetization indicates a superparamagnetic phase with magnetic clusters arranging in a spin glass state below the freezing temperature $T_f$. Magnetic structure of InSe ⟨Mn⟩ 2D-ferromagnetic single crystals was studied by SQUID magnetometry, neutron diffraction, secondary ion mass spectroscopy, and wave dispersive spectra. Hysteresis loops of magnetization were observed at least up to 350 K. The cluster model of ferromagnetism is considered. The formation of self-assembled superlattice ferromagnetic InSe:Mn/antiferromagnetic MnSe during growth process and further annealing was established