Photocurrent distribution and metal contact properties of MoTe2 field effect transistor

• Main Authors: Hung-chih Shi, 施宏志
• Other Authors: Y. W. Suen
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/57593404160763727515

碩士 === 國立中興大學 === 物理學系所 === 104 === Using Bias-Dependent Photocurrent to Study the Variation of Schottky Barrier Height in MoTe2/Metal Junctions The Schottky barrier height of the contacts in multilayer MoTe2 thin film field effect transistors (MoTe2 FETs) was studied by the photocurrent variation as the position of the excitation laser beam spot being swept through the metal-MoTe2 contacts. The laser beam has a spot size about 1.5 um and a wavelength of 633 nm. The sample was placed by a two-axis nanometer scanning stage with a 100x100 umxum scanning range. The multilayer MoTe2 thin film were obtained by exfoliation method with a Polydimethylsiloxane (PDMS) film tape, and its thickness was estimated by the contrast of optical color images, AFM and Raman spectroscopy. The line profile of the photocurrent shows that the strongest photoresponce occurs near the metal-MoTe2 junction, and the peak intensity varies with the source-drain and backgate biases. From the bias dependence of the photocurrent peak, we can extract the Schottky barrier height. Roughly two types of junctions can be obtained from this analysis: one has a good Schottky barrier the other is more like an ohmic contact.The areal mapping of the photocurrent reveals that the peak photocurrent has a very large fluctuation along the junction line between the metal and MoTe2, indicating that the barrier height is not uniform even within the same junction.