Browsing by Keywords "AlGaN"

Now showing items 1-20 of 23

    • A1GaN UV photodetectors : from micro to nano 

      Bütün, Serkan (Bilkent University, 2011)
      The absorption edge of AlGaN based alloys can be tuned from deep UV to near UV by changing the composition. This enables the use of the material in various technological applications such as military, environmental ...

    • AlGaN quadruple-band photodetectors 

      Gökkavas, Mutlu; Bütün, Serkan; Caban, P.; Strupinski, W.; Özbay, Ekmel (IEEE, 2009)
      Quadruple back-illuminated ultraviolet metal-semiconductor-metal photodetectors with four different spectral responsivity bands were demonstrated. The average of the full-width at half-maximum (FWHM) of the quantum efficiency ...

    • Contributions of impurity band and electron-electron interactions to magnetoconductance in AlGaN 

      Tasli, P.; Yildiz, A.; Kasap, M.; Özbay, Ekmel; Lisesivdin, S. B.; Ozcelik, S. (Taylor & Francis, 2010-06-30)
      Low temperature electrical measurements of conductivity, the Hall effect and magnetoconductance were performed on a degenerate AlGaN sample. The sample exhibited negative magnetoconductance at low magnetic fields and low ...

    • Design, fabrication and characterization of high-performance solarblind AlGaN photodetectors 

      Özbay, Ekmel (SPIE, 2005)
      Design, fabrication, and characterization of high-performance AlxGal-xN-based photodetectors for solar-blind applications are reported. AlxGal-xN heterostructures were designed for Schottky, p-i-n, and metal-semiconductor-metal ...

    • Determination of the in-plane effective mass and quantum lifetime of 2D electrons in AlGaN/GaN based HEMTs 

      Celik O.; Tiras, E.; Ardali, S.; Lisesivdin, S.B.; Özbay, Ekmel (2011)
      Magnetoresistance and Hall resistance measurements have been used to investigate the electronic transport properties of AlGaN/GaN based HEMTs. The Shubnikov-de Haas (SdH) oscillations from magnetoresistance, is obtained ...

    • Effect of gate structures on the DC and RF performance of AlGaN/GaN HEMTs 

      Toprak, Ahmet; Osmanoǧlu, Sinan; Öztürk, Mustafa; Yılmaz, Doğan; Cengiz, Ö.; Şen, Ö.; Bütün, Bayram; Özcan, Ş.; Özbay, Ekmel (Institute of Physics Publishing, 2018)
      This work analyzes the effect of various gate structures on the DC and radio frequency (RF) performance of AlGaN/GaN high-electron mobility transistors (HEMTs). AlGaN/GaN HEMT devices with a 3 μm drain-to-source spacing, ...

    • Fabrication and characterization of graphene/AlGaN/GaN ultraviolet Schottky photodetector 

      Kumar, M.; Jeong, H.; Polat, K.; Okyay, Ali Kemal; Lee, D. (Institute of Physics Publishing, 2016)
      We report on the fabrication and characterization of a Schottky ultraviolet graphene/AlGaN/GaN photodetector (PD). The fabricated device clearly exhibits rectification behaviour, indicating that the Schottky barrier is ...

    • GaN/AlGaN-based UV photodetectors with performances exceeding the PMTS 

      Tut, Turgut (Bilkent University, 2008)
      The recent developments in high Al-content AlxGa1−xN material growth technology made it possible to fabricate high performance solar-blind photodetectors operating in the ultraviolet (UV) spectral region with improved receiver ...

    • The growth, fabrication and characterization of high performance AI(formula)Ga(formula)N metal-semiconductor-metal photodiodes 

      Bütün, Serkan (Bilkent University, 2006)
      High performance UV photodetectors have attracted unwarranted attention for various applications, such as in military, telecommunication, and biological imaging, as an AlxGa1-xN material system is also rather suitable ...

    • High bandwidth-efficiency solar-blind AlGaN Schottky photodiodes with low dark current 

      Tut, T.; Bıyıklı, Necmi; Kimukin, I.; Kartaloglu, T.; Aytur, O.; Unlu, M. S.; Özbay, Ekmel (Pergamon Press, 2005-01)
      Al0.38Ga0.62N/GaN heterojunction solar-blind Schottky photodetectors with low dark current, high responsivity, and fast pulse response were demonstrated. A five-step microwave compatible fabrication process was utilized ...

    • High performance AlxGa1-xN-based avalanche photodiodes 

      Tut, T.; Butun, B.; Gokkavas, M.; Özbay, Ekmel (Elsevier BV, 2007-10)
      We report high performance solar-blind photodetectors with reproducible avalanche gain as high as 820 under ultraviolet illumination. The solar-blind photodetectors have a sharp cut-off around 276 nm. We improved the ...

    • High-performance solar-blind AlGaN photodetectors 

      Özbay, Ekmel; Tut, Turgut; Bıyıklı, N. (SPIE, 2005)
      Design, fabrication, and characterization of high-performance Al xGa1-xN-based photodetectors for solar-blind applications are reported. AlxGa1-xN heterostructures were designed for Schottky, p-i-n, and metal-semiconductor-metal ...

    • High-performance solar-blind photodetectors based on AlxGa 1_xN heterostructures 

      Özbay, Ekmel; Bıyıklı, Necmi; Kimukin, I.; Kartaloglu, T.; Tut, T.; Aytür, O. (IEEE, 2004)
      Design, fabrication, and characterization of high-performance AI xGa1-xN-based photodetectors for solar-blind applications are reported. AlxGa1-xN heterostructures were designed for Schottky. p-i-n, and metal-semicondnctor-metal ...

    • Improved Tmax estimation in GaN HEMTs using an equivalent hot point approximation 

      Odabaşı, Oğuz; Akar, Mehmet Ömer; Bütün, Bayram; Özbay, Ekmel (IEEE, 2020)
      In this article, heat generation distribution and maximum device temperature of gallium-nitride (GaN) high-electron-mobility transistors (HEMTs) are investigated by using the 2-D electrothermal and finite-element method ...

    • Improvement of breakdown characteristics in AlGaN/GaN/AlxGa 1-xN HEMT based on a grading Al xGa 1-xN buffer layer 

      Yu, H.; Lisesivdin, S. B.; Ozturk, M.; Bolukbas, B.; Kelekci, O.; Ozturk, M. K.; Ozcelik, S.; Caliskan, D.; Cakmak, H.; Demirel, P.; Özbay, Ekmel (Wiley, 2010-08-03)
      To improve the breakdown characteristics of an AlGaN/GaN based high electron mobility transistor (HEMT) for high voltage applications, AlGaN/GaN/Al xGa 1-xN double heterostructure (DH-HEMTs) were designed and fabricated ...

    • Integrated AlGaN quadruple-band ultraviolet photodetectors 

      Gökkavas, M.; Butun, S.; Caban, P.; Strupinski, W.; Özbay, Ekmel (IOP Publishing, 2012-04-27)
      Monolithically integrated quadruple back-illuminated ultraviolet metalsemiconductormetal photodetectors with four different spectral responsivity bands were demonstrated on each of two different Al xGa 1-xN heterostructures. ...

    • Investigation of a hybrid approach for normally-off GaN HEMTs using fluorine treatment and recess etch techniques 

      Kurt, Gökhan; Gülseren, Melisa Ekin; Salkım, Gurur; Ural, Sertaç; Kayal, Ömer Ahmet; Öztürk, Mustafa; Bütün, Bayram; Kabak, M.; Özbay, Ekmel (Institute of Electrical and Electronics Engineers Inc., 2019)
      A hybrid approach for obtaining normally off high electron mobility transistors (HEMTs) combining fluorine treatment, recess etch techniques, and AlGaN buffer was studied. The effects of process variations (recess etch ...

    • Investigation of AlGaN buffer layers on sapphire grown by MOVPE 

      Van Gemmern, P.; Dikme, Y.; Bıyıklı, Necmi; Kalisch, H.; Özbay, Ekmel; Jansen, R. H.; Heuken, M. (SPIE, 2004)
      In this work, AlGaN layers were grown on sapphire by metal-organic vapor phase epitaxy (MOVPE) on (0001)-oriented sapphire substrates, with the intention to investigate the effect of varying Al/MO and V/III ratios on the ...

    • Investigation of angstrom-thick aluminium oxide passivation layers to improve the gate lag performance of GaN HEMTs 

      Gülseren, Melisa Ekin; Kurt, Gökhan; Ulusoy Ghobadi, Türkan Gamze; Ghobadi, Amir; Salkım, Gurur; Öztürk, Mustafa; Bütün, Bayram; Özbay, Ekmel (IOP, 2019-07)
      In this paper, we report an angstrom-thick atomic layer deposited (ALD) aluminum oxide (Al2O3) dielectric passivation layer for an AlGaN/GaN high electron mobility transistor (HEMT). Our results show a 55% improvement in ...

    • Mobility limiting scattering mechanisms in nitride-based two-dimensional heterostructures with the InGaN channel 

      Gökden, S.; Tülek, R.; Teke, A.; Leach, J. H.; Fan, Q.; Xie, J.; Özgür, Ü.; Morkoç, H.; Lisesivdin, S. B.; Özbay, Ekmel (IOP Publishing, 2010-03-16)
      The scattering mechanisms limiting the carrier mobility in AlInN/AlN/InGaN/GaN two-dimensional electron gas (2DEG) heterostructures were investigated and compared with devices without InGaN channel. Although it is expected ...