Carrier dynamics and transient photobleaching in thin layers of black phosphorus

Suess, Ryan J.; Jadidi, Majid; Murphy, Thomas E.; Mittendorff, Martin

doi:10.1063/1.4929403

Cited by 79 publications

(116 citation statements)

References 23 publications

(21 reference statements)

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“…As the carriers emit phonons and relax to states closer to the band edge, the contribution from Pauli blocking diminishes, reflecting in the rise in the reflectivity signal. The second decay that starts from a few picoseconds, and is much slower, is attributed to the carrier recombination and lattice heating, and the time scales (10-100 picoseconds) are in good agreement with published work [45][46][47] . This second decay is thus an interband relaxation process.…”

Section: Resultssupporting

confidence: 89%

Mid-infrared ultrafast carrier dynamics in thin film black phosphorus

Iyer

2017

2D Mater.

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Black phosphorus is emerging as a promising semiconductor for electronic and optoelectronic applications. To study fundamental carrier properties, we performed ultrafast femtosecond pumpprobe spectroscopy on thin film black phosphorus mechanically exfoliated on a glass substrate.Carriers (electrons and holes) were excited to high energy levels and the process of carrier relaxation through phonon emission and recombination was probed. We used a wide range of probing wavelengths up to and across the band gap to study the evolution of the relaxation dynamics at different energy levels. Our experiments revealed a plethora of important physical phenomena. The fast relaxation time constants, associated with carrier-phonon scattering, steadily increase as the energy of the probe beam approaches the band gap energy, which was determined to be 0.31 eV, and the carrier recombination rate was obtained when the probe wavelength was 2 tuned to match the band gap energy. The carrier-phonon scattering rates were found to be similar along the armchair and zigzag directions, therefore, the anisotropic carrier mobility reported in literature is mainly due to the difference in effective mass of carriers along different directions.The ultrafast spectroscopy data further revealed the oxidation induced surface charges. Our results highlight the importance of using the spectroscopy technique, in this case, in the mid-IR range, to uncover useful physical processes.Since the last decade there has been an increasing interest in the study of two-dimensional materials, especially graphene and transition metal dichalcogenides (TMDC) for fabricating many electronic and optoelectronic devices [1][2][3][4][5][6][7][8][9][10][11] . Black phosphorus has emerged as a recent material in this field and has shown promises with its direct bandgap, anisotropic electronic, optical, and thermal properties, and good device performance [12][13][14][15][16][17][18][19] . Black phosphorus has a direct bandgap in the bulk of around 0.35 eV and can become as large as 1.5 eV in the monolayer form according to first principles calculations, photoluminescence studies, and electrical measurements 13, 20-24 . The direct bandgap is attractive for use in electronic devices such as solar cells 25,26 and photodetectors [27][28][29][30] . Black phosphorus has also been successfully tested as a transistor channel material [31][32][33] .Given the vast interest in black phosphorus, it is important to investigate its properties at a fundamental level. Ultrafast optical spectroscopy is very useful in understanding carrier scattering, relaxation, and recombination processes. Many ultrafast studies have been carried out on graphene [34][35][36][37][38][39][40] and TMDC such as MoS2 41-44 . There have also been a few ultrafast optical studies on black

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Section: Resultssupporting

confidence: 89%

Mid-infrared ultrafast carrier dynamics in thin film black phosphorus

Iyer

2017

2D Mater.

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“…[20][21][22] As one of the most promising photonic 2D materials, graphene is well investigated for its NLO properties and wide nanophotonic applications 13,15,37 . For comparative purposes, we also measured the graphene dispersion with the same linear optical transmission as BP.…”

Section: Excited Carrier Dynamicsmentioning

confidence: 99%

Ultrafast Nonlinear Excitation Dynamics of Black Phosphorus Nanosheets from Visible to Mid-Infrared

et al. 2016

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The recent progress on black phosphorus makes it a promising candidate material for broadband nanophotonic devices, especially operating in the mid-infrared spectral region. Here, the excited carrier dynamics and nonlinear optical response of unoxidized black phosphorus nanosheets and their wavelength dependence were systematically studied from 800 nm to 2.1 μm. The wavelength-dependent relaxation times of black phosphorus nanosheets are determined to be 360 fs to 1.36 ps with photon energies from 1.55 to 0.61 eV. In a comparative study with graphene, we found that black phosphorus has a faster carrier relaxation in near- and mid-infrared region. With regard to nonlinear optical absorption, the response of black phosphorus significantly increases from near- to mid-infrared, and black phosphorus is also confirmed to be better as saturable absorber to MoS2 in infrared region.

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“…semiconductor, BP can be expected to form excitons due to the nonequilibrium electron and hole population after optical pumping and hence to condensate the excitonic e-h state. Very recently, several research groups have studied the carrier dynamics and anisotropic dynamical response in bulk and few layer BP by using pump-probe transmission and reflection measurements [20][21][22][23][24].…”

Section: Introductionmentioning

confidence: 99%

Prolonged photo-carriers generated in a massive-and-anisotropic Dirac material

Nurmamat

Ishida

Yori

et al. 2018

Sci Rep

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Transient electron-hole pairs generated in semiconductors can exhibit unconventional excitonic condensation. Anisotropy in the carrier mass is considered as the key to elongate the life time of the pairs, and hence to stabilize the condensation. Here we employ time- and angle-resolved photoemission spectroscopy to explore the dynamics of photo-generated carriers in black phosphorus. The electronic structure above the Fermi level has been successfully observed, and a massive-and-anisotropic Dirac-type dispersions are confirmed; more importantly, we directly observe that the photo-carriers generated across the direct band gap have the life time exceeding 400 ps. Our finding confirms that black phosphorus is a suitable platform for excitonic condensations, and also open an avenue for future applications in broadband mid-infrared BP-based optoelectronic devices.

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Carrier dynamics and transient photobleaching in thin layers of black phosphorus

Cited by 79 publications

References 23 publications

Mid-infrared ultrafast carrier dynamics in thin film black phosphorus

Mid-infrared ultrafast carrier dynamics in thin film black phosphorus

Ultrafast Nonlinear Excitation Dynamics of Black Phosphorus Nanosheets from Visible to Mid-Infrared

Prolonged photo-carriers generated in a massive-and-anisotropic Dirac material

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