2 research outputs found
New Theoretical Model to Describe Carrier Multiplication in Semiconductors: Explanation of Disparate Efficiency in MoTe<sub>2</sub> versus PbS and PbSe
We present a theoretical
model to compute the efficiency of the
generation of two or more electron–hole pairs in a semiconductor
by the absorption of one photon via the process of carrier multiplication
(CM). The photogeneration quantum yield of electron–hole pairs
is calculated from the number of possible CM decay pathways of the
electron and the hole. We apply our model to investigate the underlying
cause of the high efficiency of CM in bulk 2H–MoTe2, as compared to bulk PbS and PbSe. Electronic band structures were
calculated with density functional theory, from which the number of
possible CM decay pathways was calculated for all initial electron
and hole states that can be produced at a given photon energy. The
variation of the number of CM pathways with photon energy reflects
the dependence of experimental CM quantum yields on the photon energy
and material composition. We quantitatively reproduce experimental
CM quantum yields for MoTe2, PbS, and PbSe from the calculated
number of CM pathways and one adjustable fit parameter. This parameter
is related to the ratio of Coulomb coupling matrix elements and the
cooling rate of the electrons and holes. Large variations of this
fit parameter result in small changes in the modeled quantum yield
for MoTe2, which confirms that its high CM efficiency can
be mainly attributed to its extraordinary large number of CM pathways.
The methodology of this work can be applied to analyze or predict
the CM efficiency of other materials
Arthropod data from beech canopy fogging
Arthropod data collected on 80 subplots in the Bavarian Forests Nationalpark by canopy fogging in 201