arXiv subjects

G. Alymov

Publications and source records attributed to G. Alymov.

2 recordsLinked to original sources

arXiv2020

Auger recombination in narrow band quantum well CdxHg1-xTe/CdyHg1-yTe heterostructures

We present detailed theoretical and experimental studies of Auger recombination in narrow-gap mercury cadmium telluride quantum wells (HgCdTe QWs). We calculate the Auger recombination probabilities as functions of non-equilibrium carrier density, temperature and composition of quantum wells taking into account the complex band dispersions and wave functions of the structures. Our theory is validated by comparison with measured kinetics of photoconductivity relaxation in QW with band gap of 76 meV at a temperature of 77 K. We find good agreement of theory and experiment using a single fitting parameter: the initial density of non-equilibrium carriers. The model is further used to optimize the composition of QWs and find the most suitable conditions for far-infrared lasing. Particularly, for band gap of 40 meV (lasing wavelength λ=31 μm) the lasing is favored in QWs with 6.5% cadmium fraction. We also find that at very large non-equilibrium carrier densities, the main recombination channel is associated with emission of two-dimensional plasmons and not with Auger process

cond-mat.mes-hall↗

arXiv2016

Abrupt current switching in graphene bilayer tunnel transistors enabled by van Hove singularities

In a continuous search for the energy-efficient electronic switches, a great attention is focused on tunnel field-effect transistors (TFETs) demonstrating an abrupt dependence of the source-drain current on the gate voltage. Among all TFETs, those based on one-dimensional (1D) semiconductors exhibit the steepest current switching due to the singular density of states near the band edges, though the current in 1D structures is pretty low. In this paper, we propose a TFET based on 2D graphene bilayer which demonstrates a record steep subthreshold slope enabled by van Hove singularities in the density of states near the edges of conduction and valence bands. Our simulations show the accessibility of 3.5 x 10$^4$ ON/OFF current ratio with 150 mV gate voltage swing, and a maximum subthreshold slope of (20 μV/dec)$^{-1}$ just above the threshold. The high ON-state current of 0.8 mA/μm is enabled by a narrow (~ 0.3 eV) extrinsic band gap, while the smallness of the leakage current is due to an all-electrical doping of the source and drain contacts which suppresses the band-tailing and trap-assisted tunneling.

cond-mat.mes-hall↗