Abstract
Black phosphorus nanoribbons (BPNs) might offer alternatives to narrow-gap compound semiconductors for tunable optoelectronics in infrared region. In this work we present a quantum perturbation theory on two-photon absorption (TPA) in monolayer armchair-edged black phosphorus nanoribbons (acBPNs) employing the reduced two-band model within the long-wavelength BP Hamiltonian. The matrix elements for one-photon transition have been derived and the TPA spectrum associate with intra conduction band transition and inter band transition have been drawn. The calculations predict that the TPA coefficient in acBPNs is in the magnitude of 10−6 m/W in visible region, which is 4 orders higher than the conventional semiconductor quantum dots. And in infrared region, there is a giant TPA coefficient, which is mainly contributed from intra band transitions and can reach up to10−1 m/W. The TPA peaks can be tuned both by the width of BPNs and the electron relaxation energy.
Highlights
Black phosphorus (BP), which consists of phosphorus atoms arranged to puckered layers with a honeycomb structure, is one of new two-dimensional (2D) materials [1,2,3,4,5]
Similar to graphene nanoribbons [13,14], it is predicted that the electronic structure and the transport properties of confined black phosphorous nanoribbons (BPNs) will be much more abundant compared with the infinite sample, due to its crystal orientation and width dependent electronic states
We can see that the magnitude of two-photon absorption coefficient α2 resulted from the transitions intra conduction band is about 10−1 m/W for armchair-edged black phosphorus nanoribbons (acBPNs) with width N =
Summary
Black phosphorus (BP), which consists of phosphorus atoms arranged to puckered layers with a honeycomb structure, is one of new two-dimensional (2D) materials [1,2,3,4,5]. BP has a layer-dependent direct bandgap varying from 0.3 eV for bulk BP to 2.0 eV for monolayer BP ( known as phosphorene), which can bridge the energy gap between zero-gap graphene and large-gap transition metal dichalcogenides (TMDs) [6,7,8] It is a promising candidate for near- and mid-infrared opto-electronical applications [9,10,11]. In this work we theoretically investigate the two-photon absorption properties of BPNs based on the electronic energy states obtained from the reduced two-band model within the long-wavelength BP Hamiltonian. The TPA can be tuned both by the width of BPNs and the electron relaxation energy These results can give suggestions to the optoelectronic applications as an optical limiter in visible or infrared region. It can be applied to photonic cancer therapy [24]
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