Results 1 - 10 of 6471
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[en] Changes in photoluminescence spectra an photoelectric events by transfer from layer to three-dimensional growth with formation of quanta points are considered in samples with constantly stressed layer
[en] Current-voltage characteristics of surface-irradiated photodiodes based on the InAsSbP/InAs structures are analyzed using experimental data on the distribution of electroluminescence intensity over the diode surface and taking into account thickening the current streamlines near the contacts. The influence of the potential barrier associated with the N-InAsSbP/n-InAs junction in double heterostructures on the differential resistance of diodes under zero bias, the value of the reverse current, and spreading of the forward current is discussed.
[en] We report on the nucleation and growth mechanism of self-catalyzed InAs nanowires (NWs) grown on Si (111) substrates by chemical beam epitaxy. Careful choices of the growth parameters lead to In-rich conditions such that the InAs NWs nucleate from an In droplet and grow by the vapor–liquid–solid mechanism while sustaining an In droplet at the tip. As the growth progresses, new NWs continue to nucleate on the Si (111) surface causing a spread in the NW size distribution. The observed behavior in NW nucleation and growth is described within a suitable existing theoretical model allowing us to extract relevant growth parameters. We argue that these results provide useful guidelines to rationally control the growth of self-catalyzed InAs NWs for various applications. (paper)
[en] InAs/GaAs quantum dots containing a small amount of nitrogen emit stron and narrow photoluminescence at 1.3μm. The time-resolved photoluminescence study shows that the nitrogen incorporation into InAs quantum dots does not increase the defect density
[en] Optical modulation response is used to study the influence of radiative, Shockley-Read-Hall, and Auger recombination processes on the minority carrier lifetime in a mid-wave infrared InAs/InAsSb superlattice. A comparison of calculated and measured temperature dependencies shows that the lifetime is influenced mainly by radiative recombination at low temperatures, resulting in an increase of the minority carrier lifetime from 1.8 μs at 77 K to 2.8 μs at 200 K. At temperatures above 200 K, Auger recombination increases rapidly and limits the lifetime. Shockley-Read-Hall limited lifetimes on the order of 10 μs are predicted for superlattices with lower background doping concentration
[en] We performed the proof-of-principle demonstration of photon-echo quantum memory using strain-compensated InAs quantum dot ensemble in the telecommunication wavelength range. We succeeded in transfer and retrieval of relative phase of a time-bin pulse with a high fidelity. Our demonstration suggests the possibility of realizing ultrabroadband, high time-bandwidth products, multi-mode quantum memory which is operable at telecommunication wavelength
[en] n-GaSb/n-InAs/p-GaSb heterostructure with a single InAs QW was grown for the first time by MOVPE. Photocurrent spectra were obtained at reverse bias in the range from 0 to 0.8 V. It was shown that the photocurrent increases nonlinearly. The maximum of differential photoconductivity is archived at low applied voltage up to 0.2 V. This effect was explained by electrostatic screening of electrons localized in QW.
[en] Optical, structural, and thermodynamic properties of materials can be changed by reducing their dimensions. We sequentially implanted In and As into fused silica windows in order to investigate formation and properties of InAs nano-particles. UV/VIS/NIR, FTIR in mid-IR, and far-IR spectroscopy were used to study change in electronic transitions and in vibrational modes (phonons) of the nano-particles InAs. The phonons can be confined to the surface of nano-particles and have frequencies falling between the transverse and longitudinal optical modes of the bulk material. Thermal annealing developed the formation of InAs quantum dots from as-implanted In-As system. At certain annealing temperature a change in UV/VIS transmission spectra and IR reflectance spectra indicated formation of InAs quantum dots. This is particularly evident from the absorption in IR and surface phonon bands are observed, confirming presence of quantum confined InAs
[en] We have studied the characteristics of longitudinal-optical-phonon--plasmon coupled (LOPC) mode as a function of thickness in InAs epilayers, ranging from 10 to 900 nm. The absence of LOPC modes in a scale less than exciton Bohr radius manifests the role of electron diffusion rather than the carrier screening via drift motion in surface depletion region
[en] This paper reports on the unipolar medium wavelength infrared (MWIR) InAs/GaSb/B–Al0.2Ga0.8Sb type-II superlattice (T2SL) nBn detector's photoelectrical performance. In our model, the heterojunction barrier-active region (absorber) was assumed to be decisive as the contributing dark current mechanism limiting nBn's detector performance. The voltage drop analysis on the nBn structure was introduced to estimate the bias drop on the heterojunction barrier-active region. It was assumed that the contact n+-barrier heterojunction's layer has an insignificant influence on the electrical properties of the detector. In addition, a bulk-based model with an effective band gap of T2SL material has been assumed in the device modeling. Both current–voltage (I–V) and differential resistance–area product RA(V,T), characteristics of nBn's detector were found to be dominated by diffusion and generation–recombination currents in the zero-bias and the low-bias regions. At medium values of reverse voltages, the dark current was mostly affected by trap-assisted tunneling, whereas the band-to-band tunneling revealed its contribution at high values of reverse bias (V > 0.7 V). The RA(V,T) characteristics' fitting procedure allowed estimation of both diffusion and generation–recombination lifetimes as well as the trap energy level temperature dependence within T2SL energy gap. It was predicted that at T = 77 K, the RA product and detectivity reached values of 1000 Ωcm2 and 4 × 1011 cm Hz1/2 W-1, respectively. The corresponding values at room temperature were 0.01 Ωcm2 and D* = 5 × 108 cmHz1/2 W−1, respectively. Finally, InAs/GaSb/B–Al0.2Ga0.8Sb T2SLs nBn's state of the art was compared to the performance of InAs/GaSb T2SLs PIN photodiodes and the HgCdTe bulk photodiodes operated at near-room temperature. It was shown that the RA product of the MWIR T2SLs nBn detector has reached a comparable level with the state of the art of the HgCdTe bulk photodiodes. (paper)