Browsing by Subject "MIS devices"

Now showing 1 - 3 of 3

Open Access
Capacitance-conductance characteristics of Au/Ti/Al2O3/n-GaAs structures with very thin Al2O3 interfacial layer
(Institute of Physics Publishing, 2015) Turut, A.; Karabulut, A.; Ejderha, K.; Bıyıklı, Necmi
High-k Al2O3 with metallic oxide thickness of about 3 nmon n-type GaAs substrate has been deposited by the atomic layer deposition (ALD) technique. Thus, it has been formed the Au-Ti/Al2O3/n-GaAs MIS structures. It has been seen that the MIS structure exhibits excellent capacitance-voltage (C-V) and current-voltage (I-V) properties at 300 K. The saturation current of the forward bias and reverse bias I-V characteristics was the same value. An ideality factor value of 1.10 has been obtained from the forward bias I-V characteristics. The C-Vcharacteristics of the structure have shown almost no hysteresis from +3 Vto -10 Vwith frequency as a parameter. The reverse biasC-V curves have exhibited a behavior without frequency dispersion and almost hysteresis at each frequency from 10 kHz to 1000 kHz.
Open Access
Current transport mechanisms in plasma-enhanced atomic layer deposited AlN thin films
(A I P Publishing LLC, 2015) Altuntas, H.; Ozgit Akgun, C.; Donmez, I.; Bıyıklı, Necmi
Here, we report on the current transport mechanisms in AlN thin films deposited at a low temperature (i.e., 200°C) on p-type Si substrates by plasma-enhanced atomic layer deposition. Structural characterization of the deposited AlN was carried out using grazing-incidence X-ray diffraction, revealing polycrystalline films with a wurtzite (hexagonal) structure. Al/AlN/ p-Si metal-insulator-semiconductor (MIS) capacitor structures were fabricated and investigated under negative bias by performing current-voltage measurements. As a function of the applied electric field, different types of current transport mechanisms were observed; i.e., ohmic conduction (15.2-21.5 MV/m), Schottky emission (23.6-39.5 MV/m), Frenkel-Poole emission (63.8-211.8 MV/m), trap-assisted tunneling (226-280 MV/m), and Fowler-Nordheim tunneling (290-447 MV/m). Electrical properties of the insulating AlN layer and the fabricated Al/AlN/p-Si MIS capacitor structure such as dielectric constant, flat-band voltage, effective charge density, and threshold voltage were also determined from the capacitance-voltage measurements.
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.