Browsing by Author "Chen, Wei-Chan"

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Scalable MoS2/graphene hetero-structures grown epitaxially on sapphire substrates for phototransistor applications
(2018-02-01)
Chen, Hsuan-An
;
Chen, Wei-Chan
;
Sun, Hsu
;
Lin, Chien-Chung
;
Lin, Shih-Yen
Bi-layer graphene is grown directly on sapphire substrates by using ethane as the precursor without the assistance of a metal catalyst. A growth model of graphene flake formation in the furnace, followed by a complete film growth is also proposed. Using the graphene/sapphire sample as the new substrate, scalable MoS2 films with good layer number controllability can be grown directly on the substrate. After fabricating the MoS2/graphene hetero-structures into bottom-gate photo-transistors, a Dirac point shift is observed for the device under the light irradiation condition, which is attributed to the extraction of photo-excited electrons in the MoS2 layer to the graphene channel. The photo-voltaic response observed for the photo-transistors may provide a potential application of the 2D material hetero-structure in thin-film solar cells.
Type-II Superlattice Infrared Photodetectors With Graphene Transparent Electrodes
(2017-10-01)
Chen, Hsuan-An
;
Chen, Hsuan-Yu
;
Chen, Wei-Chan
;
Lin, Shih-Yen
;
影像與生醫光電研究所
In this letter, we have demonstrated that graphene can act as a transparent electrode on the p-type GaSb substrate. Wavelength-insensitive and over 95% high transmittance are observed for the bi-layer graphene in the infrared light range. By using graphene as the transparent electrode, over ten-time responsivity enhancement is observed for the InAs/GaSb type-II superlattice infrared photodetector. The phenomenon is attributed to the shortened carrier transport paths resulted from the vertical current flow to the graphene electrode. The results have revealed the potential of graphene for the application of infrared transparent electrodes.