Browsing by Author "Ahmetoğlu, Muhitdin A."

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Current transport in GaSb /GaInAsSb/GaAlAsSb heterojunction photodiodes
(Natl Inst Optoelectronics, 2009-06) Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 16021109400
Current flow mechanisms have been studied for Liquid Phase Epitaxy (LPE) grown n-GaSb /n-GaInAsSb /p -GaAlAsSb heterostructures lattice-matched to GaSb substrates. An experimental investigation of current-voltage characteristics has been done in the temperature range from 80-300K, and have been determined the mechanism of the flow of dark current. The qualitative comparison of experimental results with theory shows that, in the high temperature region the diffusion mechanism of the current flow dominates in both, forward and reverse biases. The tunneling charge has the key role at low temperatures under both forward and reverse biases.
Dark currents in GaInAsSb based heterojunction photodiodes with a low diameter area at low temperatures
(Natl Inst Optoelectronics, 2010-04) Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 16021109400
Current flow mechanisms have been studied for Liquid Phase Epitaxy (LPE) grown n-GaSb/n-GaInAsSb/p-GaAlAsSb heterostructures with a low sensitivity area. An experimental investigation of current-voltage characteristics has been done in the temperature range from 77-210K, and have been determined the mechanism of the flow of dark current. The qualitative comparison of experimental results with theory shows that, the high temperature region the diffusion mechanism of the current flow dominates in both, forward and reverse biases. The tunneling charge the key role at low temperatures under both forward and reverse biases.
Dark currents in the uncooled InAs/InAsSbP photodiodes for the spectral range 1.6-3.5 mu m
(Natl Inst Optoelectronics, 2007-11) Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; 16021109400
The electrical characteristics of photodiode structures on the base of InAS/InAsSbP heterojunctions, that have a high room-temperature differential resistance and operate in the mid-infrared region over the wavelength range 1.6-3.5 mu m are reported. As a result of C-Vmeasurements, the obtained p-n heterojunctions were abrupt, with 1/C-2 similar to V, and the impurity concentration in the weakly doped region was (5-7)x10(15) cm(-3) at room temperature. An experimental investigation of current-voltage characteristics has been done in the temperature range 77-340 K, and have been determined the mechanism of the flow of dark currents in InAS/InAsSbP heterojunction photodiodes.
Determination of carrier concentrations in P-GaSb/n-InGaAsSb type II misaligned heterojunctions by the conductivity-magnetic field dependence
(Amer Scientific Publishers, 2013-01) Ahmetoğlu, Muhitdin A.; Kucur, Banu; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Anabilim Dalı.; 16021109400; 36903670200
We present results in studying narrow-gap misaligned heterojunctions based on InxGa1-x,AsySb1-y/GaSb solid solutions with a composition close to In As (x >= 0.80, E-g = 0.26 eV at T = 300 K). Unusual asymmetric electrical properties of the heterostructures (N-n, P-p, N-p and P-n) as well as their energy band diagrams are discussed. The ohmic behaviour of P-GaSb/n-InGaAsSb structure and diode-like I-V characteristics of the N-p, N-n and P-p junctions have been observed in the temperature region from 4.2 K up to 300 K. Concentration of the P-n structure with ohmic behavior was determined by the conductivity-magnetic field dependence.
Electrical and optical properties of the GaInAsSb-based heterojunctions for infrared photodiode and thermophotovoltaic cell application
(Elsevier, 2010-09) Andreev, Igor A.; Kunitsyna, Ekaterina V.; Mikhaǐlova, Maya P.; Yakovlev, Yu P.; Ahmetoğlu, Muhitdin A.; Kucur, Banu; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 16021109400; 36903670200
The electrical end optical characteristics of a type II double heterojunction (DH) in the GaSb/GaInAsSb/GaAlAsSb system with staggered band alignment were studied. An analysis of the photodiodes performance through the investigation into electrical and optical characteristics was carried out. The dark current mechanisms in the heterostructures were investigated at several temperatures. The experimental results show that at the low temperature region, the tunneling mechanism of the current flow dominates in both forward and reverse biases. At high temperatures region and in the range of voltage from 0.1 V to 1 V, the reverse current was defined by generation of carriers in the depletion region. Have been estimated the temperature coefficient of the shift of the long-wavelength edge of the spectral sensitivity at half-maximum as Delta lambda/Delta T = 1.6 nm/K. Quantum efficiency of 0.6-0.7 for the investigated photodiodes was reached without any antireflection coating. For GaSb/GaInAsSb/GaAlAsSb TPV cells, the internal quantum efficiency of 90% was achieved at wavelengths between 1.2 and 1.6 mu m. (C) 2010 Elsevier B.V. All rights reserved.
Electrical characteristics of Al/n-type GaAs Schottky barrier diodes at room temperature
(Natl Inst Optoelectronics, 2014-03) Asimov, Ahmed; Ahmetoğlu, Muhitdin A.; Kucur, Banu; Gücüyener, İsmet; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; Uludağ Üniversitesi/Teknik Bilimler Meslek Yüksekokulu.; 0000-0003-0783-4609; A-4861-2018; 55849632800; 16021109400; 36903670200; 15834767100
The current voltage (I-V) characteristics of metal semiconductor Al/n-GaAs (MS) Schottky diodes were measured at room temperature (300 K). In addition, capacitance-voltage-frequency (C-V-f) characteristics are investigated by considering the interface states (Nss) at frequency 1 MHz. SBD parameters such as ideality factor n, the series resistance (R-s) determined from Cheung's functions and Schottky barrier height, (phi(bo), are investigated as functions of temperature. Ideality factor, barrier height and series resistance values were found as 2.93-3.51, 0.58-1.47 eV and 0.80-0,59 Omega, respectively. The diode shows non-ideal I-V behaviour with an ideality factor greater than unity. Furthermore, the energy distribution of interface state density was determined from the forward bias I-V characteristics by taking into account the bias dependence of the effective barrier height. The results show the presence of thin interfacial layer between the metal and semiconductor. The interface distribution profile (Nss) as a function of (E-c-E-ss) was extracted from the forward-bias I-V measurements by taking into account the bias dependence of the effective barrier height and series resistance (Rs) for the Schottky diodes. The value of N-SS obtained 1.92x10(13)(eV)(-1)cm(-2).
Electrical properties inorganic-on-organic hybrid gaas/graphene oxide schottky barrier diode
(Amer Scientific Publishers, 2016-02) Okutan, Mustafa; Yakuphanoğlu, Fahrettin; Kırsoy, Ahmet; Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 56716481600; 16021109400
The Au88Ge12 alloy/n-type GaAs(100)/Graphene Oxide (GO)/Au Schottky barrier diode has been fabricated. GO has been prepared by Hummers method and deposited on the GaAs substrate by spraying method. Schottky diode was investigated under dark and light intensity by the current-voltage (I-V) characteristics of the heterojunction. Thermionic current mechanism above the barrier has been detected by current-voltage measurements. It was found that the barrier height increases and the ideality factor decreases with light intensity. The obtained results indicate that GaAs/GO diode can be used as a photosensor in optoelectronic applications. Also, Schottky diode has been measured by capacitance-voltage (C-V) and conductance-voltage (G-V) in the frequency range from 10 kHz to 1 MHz at room temperature.
Electrical properties of GaInAsSb/GaSb/GaAlAsSb Double Heterostructure with low diameter
(Polish Acad Sciences Inst Physics, 2014-02) Andreev, Igor A.; Kunitsyna, Ekaterina V.; Mikhaǐlova, Maya P.; Yakovlev, Yu P.; Kucur, Banu; Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; 36903670200; 16021109400
GaInAsSb/GaSb/GaAlAsSb double heterostructures are attractive for optoelectronic devices working in the 1.5-4.8,mu m wavelength region. In this paper, the current mechanisms of liquid phase epitaxy grown GaInAsSb based double heterostructures with 100,mu m diameter were investigated in the temperature range 77-350 K. It was found that diffusion current dominates at the high temperature (> 240 K) and small forward bias region, while generation-recombination current dominates at intermediate temperatures (242-171 K). At low temperature region (< 171 K), the tunneling mechanism of the current flow dominates in both forward and reverse biases.
Electrical properties of isotype N+-GaSb/n(0)-GaInAsSb/N+-GaAlAsSb type-II heterojunctions
(Pleiades Publishing, 2006-06-07) Andreev, Igor A.; Kunitsyna, Ekaterina V.; Mikhailova, Maya P.; Yakovlev, Yu P.; Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 16021109400
Band diagrams and current-voltage and capacitance-voltage characteristics of isotype N+-GaSb/n(0)-GaInAsSb/N+-GaAlAsSb heterostructures have been studied. Dark-current flow mechanisms have been analyzed. It is shown that a staggered type-II heterojunction can behave as a Schottky diode and its current-voltage characteristics exhibit rectifying properties over the entire temperature range 90-300 K. The thermionic-emission current predominates at high temperatures and low voltages. This current is due to thermal excitation of electrons from GaInAsSb to GaSb over the barrier at the heterointerface. A comparison of the relevant theoretical and experimental data confirmed that the tunneling charge transport mechanism plays the key role at low temperatures under both forward and reverse biases.
Electrical properties of n-Si/Cu Schottky diodes formed by electrodeposition
(Natl Inst Optoelectronics, 2007-04) Ahmetoğlu, Muhitdin A.; Alper, Mürsel; Şafak, Mürşide; Ertürk, Kadir; Gürpınar, B.; Kocak, F.; Haciismailoğlu, Muhammed Cüneyt; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-0781-3376; 0000-0002-4756-9988; AAG-8795-2021; AAE-3350-2022; K-7950-2012; 16021109400; 7005719283; 13613646100; 18036952100; 36910088200; 15843834900; 8975743500
In this paper we report the electrical characteristics of the Schottky diodes formed by electrodeposition of copper on n-Si (111) from 0.2 M CuSO4 5H(2)O + 0.5 M H3BO3 (pH=2.0) solution. Electrical measurements have been carried out at room temperature. n-Si/Cu diode current-voltage characteristics display low reverse-bias leakage currents and average barrier heights of 0.59 +/- 0.02 eV and 0.67 +/- 0.02 eV obtained from both I-V and C-V measurements at room temperature, respectively.
Gallium antimonide - Based photodiodes and thermophotovoltaic devices
(Amer Inst Physics, 2007) Andreev, Igor A.; Kunitsyna, Ekaterina V.; Mikhaǐlova, Maya P.; Yakovlev, Yu P.; Ahmetoğlu, Muhitdin A.; Ertürk, Kadir; Uludağ Üniversitesi/Fen Edebiyat Fakültesi/Fizik Bölümü.; 0000-0002-9555-6903; ABA-5148-2020; 16021109400; 18036952100
This paper briefly presents some important aspects of the GaSb-based material growth, as well as the performance of photodiodes and TPV devices for the 0.9-2.55 mu m spectral range. A reproducible technique has been developed for the production of high-speed and high-efficiency GaSb/GaInAsSb/GaAlAsSb photodiodes. The detectivity of the photodiodes, estimated from the measured noise level and monochromatic current sensitivity, in the spectral peak reaches D*(lambda(max), 1000,1)=(0.8-1.0)x10(11) W(-1)xcmxHz(1/2) at room temperature. Recently, we have adapted the technology for creating GaInAsSb (0.52-0.53 eV band gap) TPV devices. Based on the our results we believe a 0.5 eV band gap GaSb-based TPV cell with an open-circuit voltage well over 300 mV at current 2-3 A is a realistic near-term goal.
Gaussian distribution of inhomogeneous barrier height in Au/n-GaP (100) Schottky barrier diodes
(Natl Inst Optoelectronics, 2014) Özer, Metin; Güzel, Tamer; Asimov, A.; Ahmetoğlu, Muhitdin A.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 55849632800; 16021109400
The current voltage (I-V) measurements of Au/n-GaP Schottky barrier diodes (SBD) were carried out in the temperature range of 80-375 K. The values of zero-bias barrier height (phi(B0)) and ideality factor (n) ranged from 0.29 eV and 3.85 (80K) to 0.82 eV and 1.16 (375K), respectively. Such behavior of phi(B0) and n is attributed to Schottky barrier inhomogeneities by assuming a Gaussian Distribution (GD) of barrier hights (BHs) at Au/n-GaP interface. The phi(B0) vs q/(2kT) plot has been drawn to obtain evidence of a Gaussian distribution of the barrier heights,and values of phi(B0) = 0,97 eV and sigma(0) = 0.10 V for the mean barrier height and zero-bias standard deviation have been obtained from this plot, respectively. Thus a modified In (I-0/T-2) - q(2) sigma(2)(0) /2k(2)T(2)vs 1000/T plot has given mean barrier height phi(B0) and Richardson constant (A*) as 1.95 eV and 0.054 A cm(-2) K-2, respectively. The temperature dependence of the I-V characteristics of the Au/n-GaP Schottky diode have been successfully explained on the basis of thermionic emission (TE) mechanism with GD of the Schottky barrier heights (SBHs).
Narrow gap III-V materials for infrared photodiodes and thermophotovoltaic cells
(Elsevier, 2010-10) Kunitsyna, Ekaterina V.; Andreev, Igor A.; Sherstnev, Victor V.; L'Vova, T. V.; Mikhaǐlova, Maya P.; Yakovlev, Yu P.; Ahmetoğlu, Muhitdin A.; Kaynak, Gökay; Gürler, Orhan; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; AAH-1837-2021; 16021109400; 12042075600; 14019444500
The paper describes liquid phase epitaxial growth and characterization of the GaSb- and InAs-related materials for the photodiodes and thermophotovoltaic applications. It was shown that doping of the melt with holmium results in obtaining the high purity GaInAsSb and InAs layers. The passivation with the 1 M Na2S aqueous solution makes it possible to prepare flat growth surfaces of GaSb(1 0 0) and InAs(1 0 0) substrates after annealing. A reproducible technique has been developed for fabrication of the high-efficiency GaInAsSb/GaAlAsSb and InAs/InAsSbP photodiodes with the long-wavelength photosensitivity edge of 2.4 and 3.8 mu m, respectively. Room temperature detectivity in the spectral peak reaches D* = (0.8-1.0) x 10(11) W-1 cm Hz(1/2) for the GaInAsSb/GaAlAsSb photodiodes and D* = (3.0-5.0) x 109 W-1 cm Hz(1/2) for the InAs/InAsSbP devices. We have adapted the technology for thermophotovoltaic cells operating at an emitter temperature of 1000-1700 degrees
Poly(ethylene glycol dimethacrylate-co-1-vinyl-1,2,4-triazole/ carbon nanotube, single-walled)/n-GaAs Diode Formed by Surface Polymerization
(Polish Acad Sciences Inst Physics, 2016-07) Ahmetoğlu, Muhitdin A.; Kara, Ali; Kucur, Banu; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Kimya Bölümü.; 0000-0003-2457-6314; AAG-6271-2019; 16021109400; 7102824859; 36903670200
Poly(ethylene glycol dimethacrylate-co-1-vinyl-1,2,4-triazole/carbon nanotube, single-walled)/n-GaAs ([P(EGDMA-VTAZ)-CNSW]/n-GaAs) diode was fabricated by using surface polymerization method. Electrical properties were carried out at several temperatures. Dark current mechanisms were investigated by using current-voltage (I-V) measurements. It was shown that the fabricated structure exhibited rectification behaviour that makes it a good candidate for electronic device applications.
To the theory of electromotive force generated in potential barrier at ultrahigh frequency field
(World Scientific Publication, 2009-06-20) Shamirzaev, S. Kh; Gulyamov, Gafur; Gulyamov, Abdurasul Gafurovich; Dadamirzaev, M. G.; Boydedayev, S. R.; Aprailov, N.; Ahmetoğlu, Muhitdin A.; Kaynak, Gökay; Uludağ Üniversitesi/Fen-Edebiyat Fakültesi/Fizik Bölümü.; 16021109400; 12042075600
Radio-frequency (HF) quasi-potential Φ in the field of the space charge region of contact of a metalsemiconductor is explored. At the frequency, ω, greater frequency plasma fluctuations ω0 HF quasi-potential is positive, but at frequencies ω < ω0 quasi-potential Ph is negative. VAC and Schottky barrier with provision for HF quasi-potential are calculated. It is shown that HF gives an essential contribution on EMF hot carriers when frequency of wave is less in electronic gas fluctuations in layer potential barrier.