Browsing by Author "Tekcan, Burak"

Now showing 1 - 2 of 2

Open Access
Hollow-cathode plasma-assisted atomic layer deposition: A novel route for low-temperature synthesis of crystalline III-nitride thin films and nanostructures
(IEEE, 2015) Bıyıklı, Necmi; Ozgit-Akgun, Çağla; Goldenberg, Eda; Haider, Ali; Kızır, Seda; Uyar, Tamer; Bolat, Sami; Tekcan, Burak; Okyay, Ali Kemal
Hollow cathode plasma-assisted atomic layer deposition is a promising technique for obtaining III-nitride thin films with low impurity concentrations at low temperatures. Here we report our efforts on the development of HCPA-ALD processes for III-nitrides together with the properties of resulting thin films and nanostructures. The content will further include nylon 6,6/GaN core/shell and BN/AlN bishell hollow nanofibers, proof-of-concept thin film transistors and UV photodetectors fabricated using HCPA-ALD-grown GaN layers, as well as early results for InN thin films deposited by HCPA-ALD technique. © 2015 IEEE.
Open Access
Investigation of photodetectors based on iii-nitride and metal oxide thin films deposited by atomic layer deposition
(2015-05) Tekcan, Burak
Gallium Nitride (GaN), one of the most attractive optoelectronic materials today with a direct wide band gap of 3.4eV and high electron saturation velocity of, has found many applications from blue/UV LEDs to UV photodetectors, from high electron mobility transistors (HEMT) to solar cells. Traditional techniques to grow GaN films require high temperature (over 600C) processes. Such techniques cannot be used to synthesize GaN films on temperature sensitive substrates such as plastics or even paper for large area optoelectronic applications. To circumvent this setback, atomic layer deposition (ALD) stands out with its unique features such as low temperature process, precise thickness control and step coverage. Our work marks the demonstration of the first optical device on hollow cathode plasma assisted atomic layer deposition (HCPA-ALD) grown GaN films. The fabricated devices showed promising electrical and optical performance. A UV/VIS contrast ratio of 15 is obtained with very low dark current of 14pA at 20V applied bias. Annealing the films improved the device performance. Dark current was reduced more than two orders of magnitude while the responsivity was increased by two times. In the second part of the thesis, optoelectronic device applications on ALD grown ZnO layers will be presented. ZnO is also an attractive wide direct band gap semiconductor. It is utilized in many optical devices such as photodetectors and solar cells as well as thin film transistors and biomedical applications. In this work, device applications of ZnO on Silicon heterojunctions are investigated. A high rectification ratio of 103 is achieved with 80C grown ZnO-Si heterojunction photodiodes. High responsivity values are also recorded for these devices. At 350nm incident wavelength maximum responsivity of 35mA/W and at 585nm incident wavelength maximum responsivity of 90mA/W are obtained.