Research Information System
Thesis Type: Postgraduate
Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2019
Student: ÖMER AHMET KAYAL
Supervisor: SEMA BİLGE OCAK
Abstract:Photodiodes are semiconductor devices that convert light into electrical signal. When a photon with the energy equals to the band gap or more than the band gap of semiconductor strikes to photodiode creates an electron-hole pair. If sufficient electrical field is applied, current occurs by moving of electron and holes toward to anode and cathode, respectively. This current is sum of dark-current and photo-current. Photodiodes can be operated in a wide-ranged spectrum such as from infrared to X-rays. In this thesis, the GaN based p-i-n structure was growth epitaxially on sapphire substrate using Metal Organic Chemical Vapor Phase Epitaxy (MOVPE) technique. The GaN-p-i-n structure was investigated with various characterization tools such as X-ray diffraction system, Atomic Force Microscopy (AFM), Photoluminescence Mapper (PL) and Hall-effect measurement. The photodiode devices were produced on wafer which is grown using microfabrication techniques. The produced photodiodes are investigated in terms of photodiode performance such as dark-current, photo-current, responsivity and quantum-efficiency. During electrical measurements, Ultraviolet light was used as wave form radiation and e- charged beta particle was used as particle radiation. In the UV experiments, responsivity of the device was obtained as ~0,12 A/W in the reverse-bias region without internal gain. In this region, quantum efficiency is approximately % 60. Under the Beta-radiation conditions, high internal-gain was observed in all reverse-bias voltages due to highly ionizing-effect. Due to high internal-gain, responsivity of device was measured as ~0,12 A/W under the beta-radiation. The calculated quantum-efficiency of the devices was reached to 105 % due to highly ionizing-effect. In this case, it was observed that a single beta-particle with 17 keV energy can create approximately one thousand electron-hole pair in the device.