Anna Mukhtarova - Academia.edu (original) (raw)
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Papers by Anna Mukhtarova
Optics Express
Superconducting-nanowire single photon detectors (SNSPDs) are able to reach near-unity detection ... more Superconducting-nanowire single photon detectors (SNSPDs) are able to reach near-unity detection efficiency in the infrared spectral range. However, due to the intrinsic asymmetry of nanowires, SNSPDs are usually very sensitive to the polarization of the incident radiation, their responsivity being maximum for light polarized parallel to the nanowire length (transverse-electric (TE) polarization). Here, we report on the reduction of the polarization sensitivity obtained by capping NbN-based SNSPDs with a high-index SiNx dielectric layer, which reduces the permittivity mismatch between the NbN wire and the surrounding area. Experimentally, a polarization sensitivity below 0.1 is obtained both at 1.31 and 1.55 µm, in excellent agreement with simulations.
Superconductor Science and Technology
Proceedings
In the field of quantum technologies, the superconducting nanowire single photon detector [...]
Quantum Sensing and Nano Electronics and Photonics XIV, 2017
Applied Physics Letters, 2016
We report on the influence of the quantum well thickness on the effective band gap and conversion... more We report on the influence of the quantum well thickness on the effective band gap and conversion efficiency of In0.12Ga0.88N/GaN multiple quantum well solar cells. The band-to-band transition can be redshifted from 395 to 474 nm by increasing the well thickness from 1.3 to 5.4 nm, as demonstrated by cathodoluminescence measurements. However, the redshift of the absorption edge is much less pronounced in absorption: in thicker wells, transitions to higher energy levels dominate. Besides, partial strain relaxation in thicker wells leads to the formation of defects, hence degrading the overall solar cell performance.
The impact of the barrier thickness on the performance of In 0.17 Ga 0.83 N multiple-quantum-well... more The impact of the barrier thickness on the performance of In 0.17 Ga 0.83 N multiple-quantum-well (MQW) solar cells is studied. When the barrier thickness is reduced from 9.0 to 3.7 nm, the effect of the internal polarization fields on the MQW band structure results in a blueshift of the cell photoresponse. At the same time, the overlap of the fundamental electron and hole wave-functions in the quantum wells increases and the carrier extraction by field-assisted tunneling is enhanced, impacting the external quantum efficiency and fill-factor of the cells. The experimental results show that the performance of the thinner-barrier cells studied in this work is superior, or at least comparable to the performance of their thickerbarrier counterparts, in spite of the smaller total thickness of their absorbing region. This is due to their higher external quantum efficiency (37% at 370 nm) and improved fill-factor (62%), which result in a conversion efficiency of η = 0.82%.
Optics Express
Superconducting-nanowire single photon detectors (SNSPDs) are able to reach near-unity detection ... more Superconducting-nanowire single photon detectors (SNSPDs) are able to reach near-unity detection efficiency in the infrared spectral range. However, due to the intrinsic asymmetry of nanowires, SNSPDs are usually very sensitive to the polarization of the incident radiation, their responsivity being maximum for light polarized parallel to the nanowire length (transverse-electric (TE) polarization). Here, we report on the reduction of the polarization sensitivity obtained by capping NbN-based SNSPDs with a high-index SiNx dielectric layer, which reduces the permittivity mismatch between the NbN wire and the surrounding area. Experimentally, a polarization sensitivity below 0.1 is obtained both at 1.31 and 1.55 µm, in excellent agreement with simulations.
Superconductor Science and Technology
Proceedings
In the field of quantum technologies, the superconducting nanowire single photon detector [...]
Quantum Sensing and Nano Electronics and Photonics XIV, 2017
Applied Physics Letters, 2016
We report on the influence of the quantum well thickness on the effective band gap and conversion... more We report on the influence of the quantum well thickness on the effective band gap and conversion efficiency of In0.12Ga0.88N/GaN multiple quantum well solar cells. The band-to-band transition can be redshifted from 395 to 474 nm by increasing the well thickness from 1.3 to 5.4 nm, as demonstrated by cathodoluminescence measurements. However, the redshift of the absorption edge is much less pronounced in absorption: in thicker wells, transitions to higher energy levels dominate. Besides, partial strain relaxation in thicker wells leads to the formation of defects, hence degrading the overall solar cell performance.
The impact of the barrier thickness on the performance of In 0.17 Ga 0.83 N multiple-quantum-well... more The impact of the barrier thickness on the performance of In 0.17 Ga 0.83 N multiple-quantum-well (MQW) solar cells is studied. When the barrier thickness is reduced from 9.0 to 3.7 nm, the effect of the internal polarization fields on the MQW band structure results in a blueshift of the cell photoresponse. At the same time, the overlap of the fundamental electron and hole wave-functions in the quantum wells increases and the carrier extraction by field-assisted tunneling is enhanced, impacting the external quantum efficiency and fill-factor of the cells. The experimental results show that the performance of the thinner-barrier cells studied in this work is superior, or at least comparable to the performance of their thickerbarrier counterparts, in spite of the smaller total thickness of their absorbing region. This is due to their higher external quantum efficiency (37% at 370 nm) and improved fill-factor (62%), which result in a conversion efficiency of η = 0.82%.