One of the most attractive features of 2D WSe2is a tunability in its electronic and optoelectronic properties depending on the layer number. To harness such unique characteristics for device applications, high quality and easily processable heterojunctions are required and relevant layer‐number‐dependent properties must be understood. Herein, a study is reported on hybrid heterojunctions between 2D WSe2and organic molecules from one‐step solution chemistry and their layer‐number‐dependent properties. Eosin Y (EY) dye is selected as a p‐dopant and uniformly stacked on mechanically exfoliated WSe2flakes via van der Waals interaction, forming a hybrid heterojunction with a type II alignment. The EY‐WSe2heterojunction shows significantly enhanced currents compared to pristine WSe2with a lower barrier height and a longer effective screening length. The work function of the heterostructure is also lower than that of pristine WSe2. The efficient exciton dissociation and doping effect by EY are confirmed by photocurrent and photoluminescence measurements, where WSe2emission is markedly quenched by EY and exciton contribution decreases with layer number. These findings shed critical insights into layer‐number‐dependent electronic and optoelectronic properties of organic‐WSe2layers and also provide simple yet effective means to construct transition metal dichalcogenide‐based heterostructures, which should be valuable for developing layered 2D devices.
Reliable, controlled doping of 2D transition metal dichalcogenides will enable the realization of next‐generation electronic, logic‐memory, and magnetic devices based on these materials. However, to date, accurate control over dopant concentration and scalability of the process remains a challenge. Here, a systematic study of scalable in situ doping of fully coalesced 2D WSe2films with Re atoms via metal–organic chemical vapor deposition is reported. Dopant concentrations are uniformly distributed over the substrate surface, with precisely controlled concentrations down to <0.001% Re achieved by tuning the precursor partial pressure. Moreover, the impact of doping on morphological, chemical, optical, and electronic properties of WSe2is elucidated with detailed experimental and theoretical examinations, confirming that the substitutional doping of Re at the W site leads to n‐type behavior of WSe2. Transport characteristics of fabricated back‐gated field‐effect‐transistors are directly correlated to the dopant concentration, with degrading device performances for doping concentrations exceeding 1% of Re. The study demonstrates a viable approach to introducing true dopant‐level impurities with high precision, which can be scaled up to batch production for applications beyond digital electronics.
more » « less- NSF-PAR ID:
- 10455312
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Materials
- Volume:
- 32
- Issue:
- 50
- ISSN:
- 0935-9648
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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