Polarization Dependence of Photocurrent in Monolayer Molybdenum Disulphide

Mustafa Eginligil1, Bingchen Cao1, Zilong Wang1,4, Cesare Soci1,4, and Ting Yu1,2,3

1School of Physical and Mathematical Sciences, Physics and Applied Physics, Nanyang Technological University, 21 Nanyang Link, Singapore 637371.2Department of Physics, Faculty of Science, National University of Singapore, 2 Science Drive 3, Singapore 117551.3Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, 6 Science Drive 2, Singapore 117546.4Centre for Disruptive Photonic Technologies, Nanyang Technological University, 21 Nanyang Link, Singapore 637371.

PO2.112

• Spin-valley coupling in monolayer TMDs.

• Spin-dependent valley currents due to excitons• Circular photogalvanic effect (CPGE) with light helicity dependent.• Different CPGE current intensity in response to the light helicity.

Ĥ = Valley term + Spin term + Spin-valley coupling term

Valleytronics in TMDC

Monolayer MoS2 FET devices

1.7 1.8 1.9 2.0 2.1 2.2

200

300

400

500

PL

Inte

nsity

(a.

u.)

Energy (eV)

A

B

• CVD grown monolayer MoS2

• PL excited by 2.33 eV

• Photo-transistor characterization of MoS2 device

Photocurrent measurement condition

J = C1 sin 2φ + L1 sin 4φ + L2 cos 4φ + D

Polarization Dependence of Photocurrent

High polarization at 1.96 eV excitation

Degree of current polarization

• Larger ratio of when excited by 1.96 eV, compared to excitation by 2.33 eV.

• P ~ 60±30 % much larger than PL polarization.

C1 L1 L2 D 1.96 eV -3.5 -1.5 1.8 145.1 2.33 eV -0.2 -0.7 3.2 99.5

|C1|/|L2|

• Excitation by 2.33 eV: No clear P observed.