Results 1 - 10 of 2101
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[en] The paper reports on the role of the typical mapping errors in measurement of the lateral sheet current distribution Iy(x) in a superconducting tape. The sheet current is calculated indirectly, from the mapped data of the self magnetic field of the superconducting layer. The field is generated by transport or induced current in a tape. In model calculations examples of the influence of the different types of errors on false shaping of the lateral sheet current profile are given. The field mapping is made outside and over the tape. The lateral profile Bz(x, z) of the magnetic field component, perpendicular to the superconducting layer, is input to the Biot-Savart inverse procedure. In the experiment we have used superconducting tape as a sample and an InSb Hall probe with active surface 20 x 20 μm2 as a magnetic field sensor. We demonstrate the details, together with obstacles and errors encountered in measurement and subsequent evaluation. The demonstrations serve for the reader to be aware of limits in interpretation of the measured data and to overcome the natural barrier in understanding, insight and use of this fruitful method.
[en] We present a multi-segment photonic crystal coupled cavity laser device on GaSb with a microstructured internal photodiode. This monolithically integrated power monitor is added as a third segment to a coupled cavity laser and is separated from the active device by six rows of two-dimensional photonic crystals, acting as highly reflecting mirrors. There is no additional fabrication step needed to integrate this feature into the coupled cavity laser, resulting in a highly integrated laser device of only 800 μm length. The device with lasing wavelength around 1955 nm shows single mode emission over a tuning range of as large as 16 nm and exhibits output powers of up to 9 mW
[en] It is experimentally shown that a longitudinal autosoliton excited by an electric field in nonequilibrium electron-hole plasma in p-InSb moves towards the sample periphery under the effect of a transverse magnetic field. This sample region is characterized by a lowered temperature and by the fact that the unstable existence of the autosoliton leads to a cyclic process causing current oscillations in the sample circuit. An average velocity of the autosoliton motion amounts to 2 x 102-3 x 103 cm/s in a magnetic field within the range of 5962.5-22657.5 A/m
[en] Spectra of deep levels in indium antimonide in the temperature range from 4.2 to 400 K were studied by DLRS method (deep level relaxation spectra). Measurements were carried out on n+-p structures grown up by the method of liquid-phase epitaxy, as well as at prolonged n+-p transitions obtained by the Czochralski method due to change in the type of alloying impurity during growing up. Types of traps, their energy position, their concentration are determined
[en] In this work the wavelength range of GaSb-based buried tunnel junction vertical-cavity surface-emitting lasers (VCSELs) has been extended using type-II quantum wells. The developed VCSELs emit up to 4 um and operate in continuous-wave (CW) and pulsed mode until -7°C and 45°C, respectively. The maximum single-mode CW output power is 0.175 mW. A mode-hop free electro-thermal tuning of ~19 nm is achieved. These first of a kind VCSELs are highly promising for gas sensing applications.
[en] It is shown experimentally that the longitudinal magnetic field of a relatively small magnitude causes noticeable changes in velocity of autosoliton traveling in InSb samples and a visible redistribution of these autosolitons in electric field. As a result, the current oscillation frequency and amplitude in the external circuit of a sample either increases or decreases depending on the direction of longitudinal magnetic field
[en] The Hartman effect for a tunnelling particle implies that group delay time is independent of the opaque barrier width. In the present study, the tunnelling delay time in the transmission mode is studied taking into account the real band structure of an InSb-type semiconductor quantum ring and compared with that of a parabolic band structure. The system considered in this study consists of a circular loop in the presence of Aharonov-Bohm flux. It is shown that while tunnelling through an opaque barrier, the group delay time for a given incident energy becomes independent of the barrier thickness as well as the magnitude of the flux
[en] Electromodulation spectroscopy (photoreflectance and electroreflectance) is an excellent technique to study optical transitions in quantum well (QW) structures but the development of this technique in the midinfrared spectral region is still limited due to various reasons. In this work we report our recent progress in the development of contactless electroreflectance spectroscopy in midinfrared and discuss some aspects and perspectives of this technique in the context of its application to study optical transitions in GaSb-based QWs. Especially, we have focused on the band offset issue in GaInAsSb/GaSb QWs since the accurate study/verification of band gap discontinuities at QW interfaces is a crucial point in the optimization of laser structures grown on GaSb substrate and operating in the 1.8-3.0 μm spectral range.