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Nano Lett. 2019 Mar 13;19(3):1488-1493. doi: 10.1021/acs.nanolett.8b04041. Epub 2019 Feb 20.

Bright Mid-Infrared Photoluminescence from Thin-Film Black Phosphorus.

Author information

1
Department of Electrical Engineering , Yale University , New Haven , Connecticut 06511 , United States.
2
Department of Electrical and Computer Engineering , University of Illinois Urbana-Champaign , Champaign , Illinois 61801 , United States.
3
Institute for Energy Efficiency , University of California, Santa Barbara , Santa Barbara , California 93106 , United States.
4
National Institute for Materials Science , 1-1 Namiki , Tsukuba 305-0044 , Japan.

Abstract

Recently rediscovered layered black phosphorus (BP) provides rich opportunities for investigations of device physics and applications. The band gap of BP is widely tunable by its layer number and a vertical electric field, covering a wide electromagnetic spectral range from visible to mid-infrared. Despite much progress in BP optoelectronics, the fundamental photoluminescence (PL) properties of thin-film BP in mid-infrared have rarely been investigated. Here, we report bright PL emission from thin-film BP (with thickness of 4.5 to 46 nm) from 80 to 300 K. The PL measurements indicate a band gap of 0.308 ± 0.003 eV in 46 nm thick BP at 80 K, and it increases monotonically to 0.334 ± 0.003 eV at 300 K. Such an anomalous blueshift agrees with the previous theoretical and photoconductivity spectroscopy results. However, the observed blueshift of 26 meV from 80 to 300 K is about 60% of the previously reported value. Most importantly, we show that the PL emission intensity from thin-film BP is only a few times weaker than that of an indium arsenide (InAs) multiple quantum well (MQW) structure grown by molecular beam epitaxy. Finally, we report the thickness-dependent PL spectra in thin-film BP in mid-infrared regime. Our work reveals the mid-infrared light emission properties of thin-film BP, suggesting its promising future in tunable mid-infrared light emitting and lasing applications.

KEYWORDS:

Black phosphorus; anomalous blueshift; band gap; mid-infrared; photoluminescence; tunability

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