Fabrication and investigation of photodetectors based on two-dimensional GaSe doped PVP thin film

In this thesis, two dimensional GaSe flakes, one of the two-dimensional semiconductors, was doped into PVP polymer material by doping various percentage concentrations. Thin films of doped PVP+GaSe solution were coated on Si substrate by spin - coating technique. The surface morphologies of the prepared thin films were analyzed by scanning electron microscopy (SEM), thickness determination and refractive index parameters were analyzed by Ellipsometry method, structural characteristics were analyzed by X-ray diffraction (XRD) method, and optical characteristics were analyzed by Raman and Photoluminescence spectroscopy. Then, Schottky photodetectors and field effect transistors were produced with appropriate mask and fabrication techniques. In order to determine the electrical characteristics of the devices, current-voltage (I-V) and short-circuit current-time (I-t) measurements under different illumination intensities were analyzed. Important device parameters were calculated from the graphs of current-voltage measurements. Illumination dependent short-circuit current-time (I-t) measurements were also analyzed to understand photodetector performance. Parameters such as photoresponse, external quantum efficiency and detectivity were calculated from the I-t plot. According to the experimental results, it was observed that the device with PVP+5% GaSe thin film had the best photodedector performance, the best photoresponse, the highest external quantum efficiency and the highest rectification ratio values. Considering the current-voltage characteristics obtained from similar transistor experiments, it was observed that transistors with PVP+5% GaSe thin film had the best performance. This research will pave the way for novel device designs and electronic applications for new nanocomposites decorated with different 2D materials.