Browsing by Subject "Nitrogen plasma"

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Open Access
Electrical conduction and dielectric relaxation properties of AlN thin films grown by hollow-cathode plasma-assisted atomic layer deposition
(Institute of Physics Publishing, 2016) Altuntas, H.; Bayrak, T.; Kizir, S.; Haider, A.; Bıyıklı, Necmi
In this study, aluminum nitride (AlN) thin films were deposited at 200 ï¿½C, on p-type silicon substrates utilizing a capacitively coupled hollow-cathode plasma source integrated atomic layer deposition (ALD) reactor. The structural properties of AlN were characterized by grazing incidence x-ray diffraction, by which we confirmed the hexagonal wurtzite single-phase crystalline structure. The films exhibited an optical band edge around ∼5.7 eV. The refractive index and extinction coefficient of the AlN films were measured via a spectroscopic ellipsometer. In addition, to investigate the electrical conduction mechanisms and dielectric properties, Al/AlN/p-Si metal-insulator-semiconductor capacitor structures were fabricated, and current density-voltage and frequency dependent (7 kHz-5 MHz) dielectric constant measurements (within the strong accumulation region) were performed. A peak of dielectric loss was observed at a frequency of 3 MHz and the Cole-Davidson empirical formula was used to determine the relaxation time. It was concluded that the native point defects such as nitrogen vacancies and DX centers formed with the involvement of Si atoms into the AlN layers might have influenced the electrical conduction and dielectric relaxation properties of the plasma-assisted ALD grown AlN films.
Open Access
Plasma-enhanced atomic layer deposition of III-nitride thin films
(Electrochemical Society Inc., 2013) Ozgit-Akgun, Çağla; Dönmez İnci; Bıyıklı, Necmi
AlN and GaN thin films were deposited by plasma-enhanced atomic layer deposition using trimethylmetal precursors. The films were found to have high oxygen incorporation, which was attributed to oxygen contamination related to the plasma system. The choice of nitrogen containing plasma gas (N2, N2/H2 or NH3) determined the severity of oxygen incorporation into deposited films. Lowest oxygen concentrations were attained for AlN and GaN thin films using NH3 and N2 plasma, respectively. Initial experiments have shown that GaN thin films with low impurity concentrations can be deposited when plasma-related oxygen contamination is avoided by the use of an alternative plasma source. © The Electrochemical Society.