Low-temperature consecutive pulsed chemical vapor deposition of ternary BGaN and BInN thin film alloys

Haider, Ali, E-mail: ali.haider@bilkent.edu.tr, E-mail: biyikli@unam.bilkent.edu.tr Kizir, Seda Ozgit-Akgun, Cagla Biyikli, Necmi, E-mail: ali.haider@bilkent.edu.tr, E-mail: biyikli@unam.bilkent.edu.tr Okyay, Ali Kemal Institute of Materials Science and Nanotechnology, Bilkent College, Bilkent, Ankara 06800 Department of Electrical and Electronics Engineering, Bilkent College, Bilkent, Ankara 06800 Chicken

During this work, the authors have performed consecutive pulsed chemical vapor deposition of ternary BGaN and BInN alloys in the growth temperature of 450 °C. Triethylboron, triethylgallium, trimethylindium, and N or N/H plasma are really utilized as boron, gallium, indium, and nitrogen precursors, correspondingly. The authors have studied the compositional dependence of structural, optical, and morphological characteristics of BGaN and BInN ternary thin film alloys. Grazing incidence X-ray diffraction measurements proven that boron incorporation in wurtzite lattice of GaN and InN diminishes the crystallinity of BGaN and BInN sample. Refractive index decreased from 2.24 one.65 because the B power BGaN elevated from 35% to 88%. Similarly, refractive index of BInN altered from 1.98 one.74 for rise in B concentration value from 32% to 87%, correspondingly. Optical transmission band edge values within the BGaN and BInN films are actually using lower wavelengths with growing boron content, indicating the tunability of the person’s band gap with alloy composition. Atomic pressure microscopy measurements revealed a lift in surface roughness with boron power BGaN, while a contrary trend was observed for BInN thin films. less

Performance enhancement of GaN metal–semiconductor–metal ultraviolet photodetectors by insertion of ultrathin interfacial HfO layer

Kumar, Manoj, E-mail: panwarm72@yahoo.com, E-mail: aokyay@ee.bilkent.edu.tr Tekcan, Burak Okyay, Ali Kemal, E-mail: panwarm72@yahoo.com, E-mail: aokyay@ee.bilkent.edu.tr

The authors demonstrate improved device performance of GaN metal–semiconductor–metal ultraviolet (Ultra crimson) photodetectors (PDs) by ultrathin HfO (UT-HfO) layer on GaN. The UT-HfO interfacial layer is grown by atomic layer deposition. The dark current within the PDs with UT-HfO is considerably reduced by greater than two orders of magnitude in comparison to individuals without HfO insertion. The photoresponsivity at 360 nm could be 1.42 A/W biased at 5 V. A great improvement within the performance within the devices pertains to permitted electron injection through UT-HfO on GaN interface under Ultra crimson illumination, leading to themore photocurrent gain with fast response time. less

Bolat, Sami, E-mail: bolat@ee.bilkent.edu.tr Tekcan, Burak Ozgit-Akgun, Cagla Biyikli, Necmi Okyay, Ali Kemal, E-mail: aokyay@ee.bilkent.edu.tr UNAM, National Nanotechnology Research Center, Bilkent College, 06800, Ankara Institute of Materials Science and Nanotechnology, Bilkent College, 06800, Ankara

Electronic and optoelectronic devices, namely, thin film transistors (TFTs) and metal–semiconductor–metal (MSM) photodetectors, according to GaN films grown by hollow cathode plasma-aided atomic layer deposition (PA-ALD) have been proven.

Resistivity of GaN thin films and metal-GaN contact resistance are investigated as being a reason behind annealing temperature. Aftereffect in the plasma gas and postmetallization annealing across the performances within the TFTs combined with aftereffect in the annealing across the performance of MSM photodetectors are studied. Dark current to current and responsivity behavior of MSM merchandise is investigated too. TFTs while using the N/H PA-ALD based GaN channels aremore observed to possess improved stability and transfer characteristics regarding NH PA-ALD based transistors. Dark current within the MSM photodetectors is incorporated up strongly after high-temperature annealing in N:H ambient. less

Enhanced photoresponse of conformal TiO/Ag nanorod array-based Schottky photodiodes fabricated via successive glancing position and atomic layer deposition

Haider, Ali Biyikli, Necmi, E-mail: biyikli@unam.bilkent.edu.tr Cansizoglu, Hilal Cansizoglu, Mehmet Fatih Karabacak, Tansel Okyay, Ali Kemal Institute of Materials Science and Nanotechnology, Bilkent College, Bilkent, Ankara 06800 Department of Electrical and Electronics Engineering, Bilkent College, Bilkent, Ankara 06800

During this study, the authors demonstrate an evidence of concept nanostructured photodiode fabrication method via successive glancing position deposition (GLAD) and atomic layer deposition (ALD). The fabricated metal-semiconductor nanorod (NR) arrays offer enhanced photoresponse in comparison to conventional planar thin-film counterparts. Silver (Ag) metallic NR arrays were deposited on Ag-film/Si templates by utilizing GLAD. Subsequently, titanium dioxide (TiO) was deposited conformally on Ag NRs via ALD. Checking electron microscopy studies confirmed the effective formation of vertically aligned Ag NRs deposited via GLAD and conformal deposition of TiO on Ag NRs via ALD. Transporting out a progression of TiO onmore Ag NRs, aluminum metallic top contacts were created to accomplish the fabrication of NR-based Schottky photodiodes. Nanostructured devices exhibited a picture response enhancement factor of merely one.49 10 within reverse bias of three V. less

Haider, Ali Kayaci, Fatma Uyar, Tamer Biyikli, Necmi, E-mail: biyikli@unam.bilkent.edu.tr Institute of Materials Science and Nanotechnology, Bilkent College, Bilkent, Ankara 06800 Ozgit-Akgun, Cagla Okyay, Ali Kemal Institute of Materials Science and Nanotechnology, Bilkent College, Bilkent, Ankara 06800 Department of Electrical and Electronics Engineering, Bilkent College, Bilkent, Ankara 06800

Aluminum nitride (AlN)/boron nitride (BN) bishell hollow nanofibers (HNFs) are really fabricated by successive atomic layer deposition (ALD) of AlN and consecutive chemical vapor deposition (CVD) of BN on electrospun polymeric nanofibrous template. A four-step fabrication process was applied: (i) fabrication of polymeric (nylon 6,6) nanofibers via electrospinning, (ii) hollow cathode plasma-aided ALD of AlN at 100 °C onto electrospun polymeric nanofibers, (iii) calcination at 500 °C for 2 primary h to be able to eliminate the polymeric template, and (iv) consecutive CVD progression of BN at 450 °C. AlN/BN HNFs are really characterised for chemical composition, surface morphology, very structure, and internal nanostructuremore using X-ray photoelectron spectroscopy, checking electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, and selected area electron diffraction. Measurements confirmed the existence of crystalline hexagonal BN and AlN inside the 3d (3D) network of bishell HNFs with relatively low impurity content. Rather from the elegant the top of inner AlN layer, outer BN coating proven a very rough 3D morphology by means of BN nano-needle crystallites. It’s proven this mixture of electrospinning and plasma-aided low-temperature ALD/CVD can establish highly controlled multi-layered bishell nitride ceramic hollow nanostructures. While electrospinning enables easy fabrication of nanofibrous template, self-restricting reactions of plasma-aided ALD and consecutive CVD provide control of the wall thicknesses of AlN and BN layers with sub-nanometer precision. less

Amini, Rasool, E-mail: ramini2002@gmail.com Shamsipoor, Ali Ghaffari, Mohammad Alizadeh, Morteza Okyay, Ali Kemal

Mechano-synthesis of Fe–32Mn–6Si alloy by mechanical alloying within the elemental powder mixtures was evaluated by running the ball milling process under an inert argon gas atmosphere. To be able to characterize the as-milled powders, powder sampling was performed at predetermined occasions from .5 to 192 h. X-ray florescence analyzer, X-ray diffraction, checking electron microscope, and determination transmission electron microscope were selected to evaluate caffeine composition, structural evolution, morphological changes, and microstructure within the as-milled powders, correspondingly. Using the results, the nanocrystalline Fe–Mn–Si alloys were completely synthesized after 48 h of milling. Additionally, the development of the considerable amountmore of amorphous phase with the milling process was proven by quantitative X-ray diffraction analysis furthermore to top quality transmission electron microscopy image that is selected area diffraction pattern. It had been found that the -to- and subsequently the amorphous-to-crystalline (especially martensite) phase transformation happened by milling development. – Graphical abstract: Mechano-synthesis of nanocrystalline/amorphous Fe–32Mn–6Si shape memory alloys within the powder form: amorphous phase formation, -to- phase transformation, mechano-crystallization within the amorphous, and martensite phase formation in route. Highlights: • During MA, the -to- phase transformation and amorphization happened. • Mechano-crystallization within the amorphous phase happened at sufficient milling time. • The development of huge amounts of -martensite was evidenced at high milling occasions. • The platelet, spherical, then irregular particle shapes was extended by MA. • By MA, the particles size was elevated, then reduced, and afterward re-elevated. less