Now showing items 1-19 of 19

    • 97 percent light absorption in an ultrabroadband frequency range utilizing an ultrathin metal layer: randomly oriented, densely packed dielectric nanowires as an excellent light trapping scaffold 

      Ghobadi, A.; Dereshgi, S. A.; Hajian, H.; Birant, G.; Butun, B.; Bek, A.; Özbay, Ekmel (Royal Society of Chemistry, 2017)
      In this paper, we propose a facile and large scale compatible design to obtain perfect ultrabroadband light absorption using metal-dielectric core-shell nanowires. The design consists of atomic layer deposited (ALD) Pt ...
    • Alteration of spontaneous emission in hydrogenated amorphous silicon nitride microcavities 

      Serpengüzel, A.; Aydınlı, Atilla; Bek, A. (Elsevier BV, 1998)
      A Fabry-Perot microcavity is used for the alteration of the spontaneous emission spectrum in hydrogenated amorphous silicon nitride. The modified photon density of states of the Fabry-Perot microcavity are responsible for ...
    • Engineering nonlinear response of nanomaterials using Fano resonances 

      Turkpence, D.; Akguc G.B.; Bek, A.; Tasgin, M.E. (Institute of Physics Publishing, 2014)
      We show that nonlinear optical processes of nanoparticles can be controlled by the presence of interactions with a molecule or a quantum dot. By choosing the appropriate level spacing for the quantum emitter, one can either ...
    • Enhancement and inhibition of photoluminescence in hydrogenated amorphous silicon nitride microcavities 

      Serpenguzel, A.; Aydınlı, Atilla; Bek, A. (Optical Society of America, 1997-09-01)
      A Fabry-Perot microcavity is used for the enhancement and inhibition of photoluminescence in hydrogenated amorphous silicon nitride. The amplitude of the photoluminescence is enhanced 4 times, while its linewidth is reduced ...
    • Fabrication of 15- $\mu$ m pitch $640{\rm ×}512$ InAs/GaSb type-II superlattice focal plane arrays 

      Oğuz, Fikri; Arslan, Y.; Ülker, E.; Bek, A.; Özbay, Ekmel (Institute of Electrical and Electronics Engineers Inc., 2019)
      We present the fabrication of large format 640 × 512, 15-μm pitch, mid-wave infrared region (MWIR) InAs/GaSb type-II superlattice (T2SL) focal plane array (FPA). In this report, the details of device design and fabrication ...
    • In-chip microstructures and photonic devices fabricated by nonlinear laser lithography deep inside silicon 

      Tokel, O.; Turnalı, A.; Makey, G.; Elahi, P.; Çolakoǧlu, T.; Ergeçen E.; Yavuz, Ö.; Hübner R.; Borra, M. Z.; Pavlov, I.; Bek, A.; Turan, R.; Kesim, D. K.; Tozburun, S.; Ilday, S.; Ilday, F. Ö. (Nature Publishing Group, 2017)
      Silicon is an excellent material for microelectronics and integrated photonics 1-3, with untapped potential for mid-infrared optics 4 . Despite broad recognition of the importance of the third dimension 5,6, current ...
    • Laser-slicing of silicon with 3D nonlinear laser lithography 

      Tokel, Onur; Turnalı, Ahmet; Çolakoğlu, T.; İlday, Serim; Borra, M. Z.; Pavlov, Ihor; Bek, A.; Turan, R.; İlday, Fatih Ömer (OSA, 2017)
      Recently, we have showed a direct laser writing method that exploits nonlinear interactions to form subsurface modifications in silicon. Here, we use the technique to demonstrate laser-slicing of silicon and its applications.
    • Lithography-Free random bismuth nanostructures for full solar spectrum harvesting and mid-infrared sensing 

      Soydan, Mahmut Can; Ghobadi, Amir; Yıldırım, Deniz Umut; Duman, E.; Bek, A.; Ertürk, Vakur Behçet; Özbay, Ekmel (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2020)
      A lithography‐free, double‐functional single bismuth (Bi) metal nanostructure is designed, fabricated, and characterized for ultrabroadband absorption in the visible (vis) and near‐infrared (NIR) ranges, and for a narrowband ...
    • Low dark current diffusion limited planar type InGaAs photodetectors 

      Dolaş, M. Halit; Ateşal, Okan; Çalışkan, M. Deniz; Bek, A.; Özbay, Ekmel (SPIE, 2019)
      In this work, we design and produce 1280x1024 format InGaAs based planar type detectors with 15μm pixel pitch. We have obtained diffusion current limited low dark current (~10fA) and high responsivity (1.08A/W at 1.55μm) ...
    • Low-temperature photoluminescence spectra of layered semiconductor TlGaS2 

      Gasanly, N. M.; Aydınlı, Atilla; Bek, A.; Yilmaz, I. (Pergamon Press, 1998)
      Photoluminescence (PL) spectra of TlGaS2 layered single crystals were studied in the wavelength region 500-860 nm and in the temperature range 9.5-293 K. We observed a total of three PL bands centered at 568 nm (2.183 eV, ...
    • A magnetization and GMR study on multilayered Fe/Ag/Co thin film 

      Birlikseven, C.; Bek, A.; Durusoy H.Z. (1999)
      Single layer Fe(20Å) and Co(20Å) and multilayered Ag(20Å)/[Fe(20Å)/Ag(40Å) /Co(20Å)/Ag (40Å)]x3 /Ag(20Å) films were prepared in UHV by magnetron sputtering technique onto the silicon substates. Films were determined to ...
    • Nanosphere concentrated photovoltaics with shape control 

      Esmaeilzad, N. S.; Demir, Ahmet Kemal; Hajivand, J.; Çiftpınar, H.; Turan, R.; Kurt, H.; Bek, A. (Wiley, 2020-12)
      Dielectric colloidal nanospheres (NSs) are promising candidates for light management in photonic devices such as solar cells (SCs). NS arrays can direct the broad incident solar radiation into a set of tighter foci, at ...
    • Nonlinear laser lithography for photonic design of si solar cells 

      Pavlov, Ihor; Çolakoğlu, T.; Es, F.; Bek, A.; Turan, R.; Gnilitskyi, I.; İlday, F. Ömer (IEEE, 2015)
      Nowadays Si-based solar cell (SC) remains the main source of solar energy in the world due to low cost of material and relatively simple, industrially acceptable technology. Despite of significant progress on increasing ...
    • Slicing crystalline silicon wafer by deep subsurface laser processing and selective chemical etching 

      Borra, M. Z.; Nasser, H.; Çiftpınar, E. H.; Turnalı, Ahmet; Deminskyi, Petro; Çolakoğlu, T.; Tokel, Onur; İlday, Fatih Ömer; Pavlov, I.; Turan, R.; Bek, A. (Institute of Electrical and Electronics Engineers Inc., 2019)
      In this work, we demonstrate use of laser-induced silicon slicing (LASIS) technique to fabricate crystalline silicon (c-Si) slices [1]. In LASIS method, a nanosecond-pulsed fiber laser operating at 1.55 μm wavelength, ...
    • Study of wet oxidized AlxGa1-xAs for integrated optics 

      Bek, A.; Aydınlı, Atilla; Champlain, J. G.; Naone, R.; Dagli, N. (Institute of Electrical and Electronics Engineers, 1999)
      An investigation of wet oxidized AlxGa1-xAs layers in integrated optical applications is reported. Refractive index and thickness shrinkage of wet oxidized AlxGa1-xAs layers are measured using spectroscopic ellipsometry. ...
    • Super-radiant surface emission from a quasi-cavity hot electron light emitter 

      O'Brien, A.; Balkan, N.; Boland-Thoms, A.; Adams, M.; Bek, A.; Serpengüzel, A.; Aydınlı, A.; Roberts, J. (Springer New York LLC, 1999)
      The Hot Electron Light Emitting and Lasing in Semiconductor Heterostructure (HELLISH-1) device is a novel surface emitter which utilises hot carrier transport parallel to the layers of a Ga1 - xAlxAs p-n junction incorporating ...
    • Temperature dependence of absorption edge in p-type porous silicon 

      Bek, A.; Aydınlı, Atilla (1998)
      The observed blue shift of both the PL and the absorption edge in porous silicon is generally understood within the framework of quantum confinement of carriers in small crystallites where reduction of the density of states ...
    • Understanding the plasmonic properties of dewetting formed Ag nanoparticles for large area solar cell applications 

      Günendi, M.C.; Tanyeli I.; Akgüç G.B.; Bek, A.; Turan, R.; Gülseren O. (Optical Society of American (OSA), 2013)
      The effects of substrates with technological interest for solar cell industry are examined on the plasmonic properties of Ag nanoparticles fabricated by dewetting technique. Both surface matching (boundary element) and ...
    • Visible photoluminescence from planar amorphous silicon nitride microcavities 

      Serpengüzel, A.; Aydınlı, Atilla; Bek, A.; Güre, M. (Optical Society of America, 1998)
      Fabry-Perot microcavities were used for the enhancement and inhibition of photoluminescence (PL) in a hydrogenated amorphous silicon nitride (a-SiNx:H) microcavity fabricated with and without ammonia. A planar microcavity ...