Browsing by Subject "SiC"

Now showing 1 - 7 of 7

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Extraction and scattering analyses of 2D and bulk carriers in epitaxial graphene-on-SiC structure
(Elsevier BV, 2014-09) Lisesivdin, S. B.; Atmaca, G.; Arslan, E.; Çakmakyapan S.; Kazar, Ö.; Bütün, S.; Ul-Hassan, J.; Janzén, E.; Özbay, Ekmel
Hall effect measurements of a graphene-on-SiC system were carried out as a function of temperature (1.8-200 K) at a static magnetic field (0.51) With the analysis of temperature dependent single-field Hall data with the Simple Parallel Conduction Extraction Method (SPCEM), bulk and two-dimensional (2D) carrier densities and mobilities were extracted successfully. Bulk carrier is attributed to SIC substrate and 2D carrier is attributed to the graphene layer. For each SPCEM extracted carrier data, relevant three-dimensional or 2D scattering analyses were performed. Each SPCEM extracted carrier data were explained with the related scattering analyses. A temperature independent mobility component, which may related to an interaction between graphene and SIC, was observed for both scattering analyses with the same mobility limiting value. With the SPCEM, effective ionized impurity concentration of SiC substrate, extracted 2D-mobility, and sheet carrier density of the graphene layer are calculated with using temperature dependent static magnetic field Hall data. (c) 2014 Elsevier B.V. All rights reserved.
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GaN based LNA MMICs for X-band applications
(Institute of Electrical and Electronics Engineers, 2020) Zafar, Salahuddin; Osmanoğlu, Sinan; Öztürk, Mustafa; Çankaya, Büşra; Yılmaz, Doğan; Kashif, A. U.; Özbay, Ekmel
In this paper, we report two low noise broadband amplifiers based on ABMN's AlGaN/GaN on SiC HEMT technology for X-band applications. Two design topologies, a single-stage (LNA-1) and a two-stage (LNA-2), have been investigated. LNA-1 and the first stage of LNA-2 is based on common source (CS) with inductive source degeneration topology. LNA-1 has a flat gain response of ±1.4 dB gain variation with a gain greater than 8 dB for 9 V drain voltage and 100 mA/mm drain current. Input return loss better than 9.8 dB and output return loss better than 12.8 dB have been achieved. The simulated value of noise figure for this design is less than 1.4 dB. In LNA-2 design, a two-stage topology is implemented to enhance amplifier's gain. The simulated values for LNA-2 show a gain greater than 16.8 dB with ±2.9 dB gain variation. Input and output return loss values are better than 8.8 dB and 10 dB, respectively. The value of noise figure for this design is less than 1.7 dB in the desired frequency range. Both designs, having state-of-the art small dimensions, are suitable for their potential applications for space communications, Radar, satellite communications etc.
Open Access
GaN-based single stage low noise amplifier for X-band applications
(IEEE, 2022-07-18) Çağlar, Gizem Tendürüs; Aras, Yunus Erdem; Urfalı, Emirhan; Yılmaz, Doğan; Özbay, Ekmel; Nazlıbilek, Sedat
Source degenerated HEMTs are used to achieve good noise matching and better input return loss without degrading the noise figure and reducing the stability. This work presents an MMIC design for the frequency band of 8–11 GHz by using HEMTs with source degeneration in 0.15 µm GaN on SiC technology. All design work is done in the Advanced Design System. The LNA delivers more than 6.9 dB gain with better than 8.5 dB and 9.5 dB input and output return losses, respectively. In addition, the gain ripple is around 2.7 dB. The noise figure of the amplifier is achieved below 1.1 dB with P1dB of 17.2 dBm and %12.7 drain efficiency within the operating bandwidth at the bias conditions of 9 V /20 mA.
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GaN-on-SiC LNA for UHF and L-Band
(IEEE, 2019) Zafar, Salahuddin; Osmanoğlu, Sinan; Çankaya, Büşra; Kashif, A.; Özbay, Ekmel
In this paper, we report a broadband GaN HEMT LNA from 100 MHz to 2 GHz, using common source with inductive degeneration and RC feedback topology. Flat gain response of ±1.5 dB variation for 9 V drain voltage with 108 mA drain current bias is achieved. Noise characteristics for frequencies as low as 100 MHz have been explored for the first time for GaN-on-SiC technology. A gain greater than 8 dB with single stage, and promising values of input reflection coefficient (smaller than -8.9 dB) and output reflection coefficient (smaller than -7.1 dB) have been achieved, respectively. Minimum NF of 2.9 dB is achieved while an NF smaller than 5 dB is reported in the usable frequency range from 310 MHz to 2 GHz. Performance evaluation is also done for both low and high drain current and voltage values. In-house 0.15 μm GaN-on-SiC process is used to design this MMIC. The chip size for designed MMIC is 1.35 mm × 1.35 mm.
Open Access
Plasmon and phonon polaritons in planar van der Waals heterostructures
(Elsevier, 2023) Hajian, Hodjat; Erçağlar, Veysel; Özbay, Ekmel
The investigation of the characteristics of plasmon polaritons and phonon polaritons in planar systems is one of the key tools in understanding the optical response of plasmonic and phononic waveguides, metamaterials, and metasurfaces. Due to the considerable research interest in the polaritonics of van der Waals (vdW) materials in recent years, we conducted a detailed study on the infrared isotropic/anisotropic polaritons in plasmonic and phononic van der Waals heterostructures.
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Synthesis, characterization, and wear and friction properties of variably structured SiC/Si elements made from wood by molten Si impregnation
(2012) Dhiman, R.; Rana, K.; Bengu, E.; Morgen P.
We have synthesized pre-shaped SiC/Si ceramic material elements from charcoal (obtained from wood) by impregnation with molten silicon, which takes place in a two-stage process. In the first process, a porous structure of connected micro-crystals of β-SiC is formed, while, in the second process, molten Si totally or partly infiltrates the remaining open regions. This process forms a dense material with cubic (β-)SiC crystallites, of which the majority is imbedded in amorphous Si. The synthesis of preshaped "sprocket" elements demonstrates that desired shapes of such a dense SiC/Si composite ceramic material can be achieved, thus suggesting new industrial applications. The structure and composition of numerous as-synthesized samples were characterized in detail by using a wide range of techniques. Wear and friction properties were also investigated, with polished samples. The properties found for the present samples are very promising for abrasive applications and for new generation brake systems. © 2011 Elsevier Ltd.
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Temperature-dependence of a GaN-based HEMT monolithic X-band low noise amplifier
(IEEE, 2004-10) Schwindt, R. S.; Kumar, V.; Aktaş, Ozan; Lee, J.-W.; Adesida, I.
The temperature-dependent performance of a fully monolithic AlGaN/GaN HEMT-based X-band low noise amplifier is reported. The circuit demonstrated a noise figure of 3.5 dB, gain of 7.5 dB, input return loss of -7.5 dB, and output return loss of -15 dB at 8.5 GHz at room temperature. The noise figure at 9.5 GHz increased from 2.5 dB at 43°C to 5.0 dB at 150°C. © 2004 IEEE.