Fabrication of organic-based photodiode and determination of its parameters for the optoelectronic applications

In this thesis, the organic based heterojunction devices were fabricated by depositing Brilliant Blue (BB) on n-Si wafer via spin coating method and evaporating Cu metal on the film with thermal evaporation technique. Electrical and photoelectrical property of fabricated devices have been investigated. Current-voltage measurements for Cu/n-Si/Au and Cu/BB/n-Si/Au were performed in the dark and at room temperature. The main electrical parameters of devices were determined using experimental and theoretical methods such as thermionic emission theory, Cheung and modified Norde functions, and obtained results were compared each other. The results show that inserting organic interlayer cause to enhance the electrical properties of the prepared devices such as better rectification behavior, higher barrier height and lower series resistance. Additionally, the frequency dependent capacitance-voltage measurement was carried out at room temperature for devices. It was noticed that the device cannot flow A.C signals at high frequencies, thus exhibit low capacitive property. Furthermore, the current-voltage measurements were carried out under various light illuminations in the range between 30-100 mW/cm2. The obtained results show that reverse bias photocurrent is strongly dependent on incident illumination power. The device also represents a high responsivity for incident light intensities. In addition, it was recognized that the device is capable to detect small amount of light intensity at low reverse voltages.