574 research outputs found
Tunneling Recombination in Optically Pumped Graphene with Electron-Hole Puddles
We evaluate recombination of electrons and holes in optically pumped graphene
associated with the interband tunneling between electron-hole puddles and
calculate the recombination rate and time. It is demonstrated that this
mechanism can be dominant in a wide range of pumping intensities. We show that
the tunneling recombination rate and time are nonmonotonic functions of the
quasi-Fermi energies of electrons and holes and optical pumping intensity. This
can result in hysteresis phenomena.Comment: 4 pages, 3 figure
Electrically-induced n-i-p junctions in multiple graphene layer structures
The Fermi energies of electrons and holes and their densities in different
graphene layers (GLs) in the n- and p-regions of the electrically induced n-i-p
junctions formed in multiple-GL structures are calculated both numerically and
using a simplified analytical model. The reverse current associated with the
injection of minority carriers through the n- and p-regions in the
electrically-induced n-i-p junctions under the reverse bias is calculated as
well. It is shown that in the electrically-induced n-i-p junctions with
moderate numbers of GLs the reverse current can be substantially suppressed.
Hence, multiple-GL structures with such n-i-p junctions can be used in
different electron and optoelectron devices.Comment: 7 pages, 6 figure
Plasma mechanisms of resonant terahertz detection in two-dimensional electron channel with split gates
We analyze the operation of a resonant detector of terahertz (THz) radiation
based on a two-dimensional electron gas (2DEG) channel with split gates. The
side gates are used for the excitation of plasma oscillations by incoming THz
radiation and control of the resonant plasma frequencies. The central gate
provides the potential barrier separating the source and drain portions of the
2DEG channel. Two possible mechanisms of the detection are considered: (1)
modulation of the ac potential drop across the barrier and (2) heating of the
2DEG due to the resonant plasma-assisted absorption of THz radiation followed
by an increase in thermionic dc current through the barrier. Using the device
model we calculate the frequency and temperature dependences of the detector
responsivity associated with both dynamic and heating (bolometric) mechanisms.
It is shown that the dynamic mechanisms dominates at elevated temperatures,
whereas the heating mechanism provides larger contribution at low temperatures,
T=35-40 K.Comment: 7 pages, 4 figure
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