PO2.112
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.
Valleytronics in TMDC
•
Spin-valley coupling in monolayer TMDs.
Ĥ = Valley term + Spin term + Spin-valley coupling term
•
•
•
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.
Monolayer MoS2 FET devices
• CVD grown monolayer MoS2
• PL excited by 2.33 eV
• Photo-transistor
characterization of MoS2 device
PL Intensity (a. u.)
500
A
400
300
B
200
1.7
1.8
1.9
2.0
2.1
2.2
Energy (eV)
Photocurrent measurement condition
Polarization Dependence of Photocurrent
High polarization at 1.96 eV excitation
J = C1 sin 2φ + L1 sin 4φ + L2 cos 4φ + D
1.96 eV
2.33 eV
C1
L1
L2
D
-3.5
-0.2
-1.5
-0.7
1.8
3.2
145.1
99.5
Degree of current polarization
𝑃𝐶 ↺ − 𝐿2 − 𝐷 − 𝑃𝐶 ↻ − 𝐿2 − 𝐷
𝑃(↺, ↻)=
𝑃𝐶 ↺ − 𝐿2 − 𝐷 + 𝑃𝐶 ↻ − 𝐿2 − 𝐷
•
Excitation by 2.33 eV: No clear P observed.
𝑃 = |C1|/|L2|
• Larger ratio of when excited by 1.96 eV,
compared to excitation by 2.33 eV.
•
P ~ 60±30 % much larger than PL polarization.