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Identifier

000403270

Title

Study of visible and infrared sensors based on two dimensional materials

Alternative Title

Μελέτη αισθητήρων ορατής και υπέρυθρης ακτινοβολίας βασισμένους σε διδιάστατα υλικά

Author

Σταυρακάκη, Αλεξάνδρα Γ.

Thesis advisor

Γεωργακίλας, Αλέξανδρος

Reviewer

Χατζόπουλος, Ζαχαρίας
Σαββίδης, Παύλος
Δεληγεώργης, Γεώργιος

Abstract

Detection of light (photodetection) is the prominent issue which has been widely investigated the recent decades by the research community in optoelectronics and used for applications in biomedical imaging, molecular sensing and telecommunication. Transition metal dichalcogenides (TMDs) belong to the family of 2 dimensional (2D) materials. They exhibit great optical properties and have attracted the interest of optoelectronic research. The scope of this thesis is to construct and investigate photodetecting devices based on MoS₂, a member of the 2D – TMDs group. MoS2 was used through a dispersion (liquid phase exfoliated MoS₂) in order to fabricate a significant amount of devices for testing. Raman analysis was used for the characterization of the deposited MoS₂ films. From Raman spectra a trilayer form of MoS₂ crystal was estimated. The photodetectors that were tested were fabricated with different metal electrodes and deposited on different substrates. Concerning the first samples, MoS₂ was deposited on Si/SiO₂ substrate with asymmetric Pt/Ti metal contacts. Electrical measurements were carried out for testing the operation of the devises without illumination (dark current measurements) revealing non – linear and symmetric I – V characteristics. The devices were also tested under illumination (photocurrent measurements) using a laser beam of wavelength ι = 405nm, where a non – linear photoresponse was measured as a function to incident laser power. The second series of samples contains MoS₂ on glass substrate with symmetric Au metal electrodes. According the respective I – V characteristics (dark current) an ohmic – like behavior was observed. Under illumination a linear dependence of photocurrent to incident power was measured. From power dependence measurements responsivity at the order of nA/W was calculated and quantum efficiency was also extracted from the power of light incident to the area of the material (MoS₂).

Language

English

Subject

MoS2

Photocurrent

Photodetectors

Responsivity

Αισθητήρες

Απόκριση

Δισουλφίδιο του Μολυβδαινίου

Φωτόρευμα

Issue date