Structural, morphological, and optical properties of AlGaN/GaN heterostructures with AlN buffer and interlayer

Çörekçí, S.; Öztürk, Mustafa Kemal; Akaoglu, Baris; Çakmak, M.; Özçelik, Süleyman; Özbay, Ekmel

doi:10.1063/1.2747216

Cited by 40 publications

(14 citation statements)

References 36 publications

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“…Therefore, GaN and some other compounds have been studied extensively for their applications in short wavelength optical and high-power/temperature devices, such as light emitting diodes (LEDs), laser diodes (LDs), metal-semiconductor (MS) Schottky barrier diodes (SBDs), metal-insulator-semiconductor high-electron-mobility transistors (MISHEMTs). GaN high-electron-mobility transistors (HEMTs) with Schottky/rectifier metal contact have demonstrated excellent highfrequency, high-power, high temperature and recently good microwave-noise characteristics [1][2][3][4][5][6][7][8][9][10]. The performance level of GaN/ AlGaN HEMT devices has increased rapidly over the last few years.…”

Section: Introductionmentioning

confidence: 99%

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

Tekeli

Gökçen

Altındal

et al. 2011

Microelectronics Reliability

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a b s t r a c tThe voltage (V) and frequency (f) dependence of dielectric characteristics such as dielectric constant (e 0 ), dielectric loss (e 00 ), dielectric loss tangent (tan d) and real and imaginary part of electrical modulus (V 0 and M 00 ) of the (Ni/Au)/GaN/Al 0.3 Ga 0.7 N heterostructures have been investigated by using experimental admittance spectroscopy (capacitance-voltage (C-V) and conductance-voltage (G/w-V)) measurements at room temperature. Experimental results show that the values of the e 0 , e 00 , tan d and the real and imaginary parts of the electric modulus (V 0 and M 00 ) obtained from the C and G/w measurements were found to be strong function of frequency and applied bias voltage especially in depletion region at low frequencies. These changes in dielectric parameters can be attributed to the interfacial GaN cap layer, interface polarization and a continuous density distribution of interface states and their relaxation time at metal/semiconductor interface. While the values of the e 0 decrease with increasing frequencies, tan d, V 0 and M 00 increase with the increasing frequency. Also, the dielectric loss (e 00 ) have a local maximum at about frequency of 100 kHz. It can be concluded that the interface polarization can occur more easily at low frequencies with the number of interface states located at the metal/semiconductor interface.

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Section: Introductionmentioning

confidence: 99%

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

Tekeli

Gökçen

Altındal

et al. 2011

Microelectronics Reliability

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“…In Figure.5 Chen and co-workers reported that In vacancy islands on the surface of the samples or ordered vacancy rows caused lateral segregation [22]. The surface roughness of the samples may be attributed to In segregation and white rust [23]. White rust can be seen on the surface of both samples in AFM images.…”

Section: Afmmentioning

confidence: 84%

XRD vs Raman for InGaN/GaN Structures

et al. 2020

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In this study, InGaN/GaN structures are grown by using Metal Organic Chemical Vapor Deposition (MOCVD) technique. Some structural, optical and morphological properties of InGaN/GaN structures are investigated in detail. For structural analysis, X-ray diffraction (XRD), for optical, Raman and morphological, Atomic Force Microscopy (AFM) measurement techniques are used. In XRD analysis both samples presented hexagonal crystal structure. XRD peaks for these two samples showed small differences dependent on growth conditions. Strain and stress values are determined from XRD and they are compared with Raman results. In Raman analysis, five different chemicals are determined in both samples. Raman analysis results are in good accordance with XRD, growth conditions and AFM images. In AFM images, there can be seen hills and holes and they are partly homogeneous. There are also some white regions in AFM images. According to Raman peak center data, these white regions are detected as white rust.

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“…[1][2][3][4] Due to lack of native GaN substrates, heteroepitaxy raises a challenge for the good structural quality, which is a must for device applications, but there are ways to achieve it by molecular beam epitaxy and metalorganic chemical vapor deposition. [5][6][7][8][9][10] However, sapphire (Al 2 O 3 ) is used as a substrate for growth of III-N based epitaxial layer in spite of its larger lattice mismatch and larger thermal expansion coefficient by taking diverse growth approaches. 11,12 Notably, in these devices, AlGaN alloys are used as barrier layers, leading to excellent carrier confinement at AlGaN/GaN interface without intentional doping.…”

Section: Introductionmentioning

confidence: 99%

Structural, optical, and transport properties of AlGaN/GaN and AlGaN/InGaN heterostructure on sapphire grown by plasma assisted molecular beam epitaxy

Jana

Ghosh

Dinara

et al. 2015

Journal of Vacuum Science &Amp; Technology B, Nanotechnology and Microelectronics: Materials, Processing, Measurement, and Phen

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The effects of indium on the strain states, surface morphologies, and polarization induced charges (and in turn on sheet carrier concentrations) at the interfacial channel layers of AlGaN/GaN and AlGaN/InGaN specimens have been investigated. Room temperature Raman spectroscopy was performed to explain the residual strains by the optical phonon frequency shift from their bulk values, and also to analyze the quality of the GaN and InGaN channel layer by the full width at half maxima of E2high and A1(LO) (longitudinal-optical) phonon lines. The strain state was also analyzed by room temperature photoluminescence (PL) spectra by observing the direct excitonic transition from Γ6v →Γ1c (A, B) for valance band to conduction band. The surface morphology was observed from atomic force microscopy imaging inferring pit densities of 4.4×107 cm−2 and 6×107 cm−2 for 5×5 μm area scans. In addition, the screw and edge type defect density were 3.28×107 and 5.85×109; 2.40×108 and 4.91×109 cm−2 as calculated from high resolution x-ray diffraction pattern (HRXRD) analysis for AlGaN/GaN and AlGaN/InGaN heterostructure, respectively. The homogeneity of the epilayers were confirmed by measuring (20 × 20 mm2) areal scans of omega-rel diffraction profiles. In addition, the theoretical estimation of carrier confinement at the interfacial two-dimensional electron gas concentration (2DEG) was carried out from analytical expressions accounting both polarization effects (spontaneous and piezoelectric) and interdependence of sheet density with Fermi level in the Ga(Al) face terminated AlGaN/GaN (or AlGaN/InGaN) airy quantum well. The calculated charge density for AlGaN/GaN and AlGaN/InGaN were found to be 1.60×1013 and 1.75×1013 cm−2 using in-plane strain values from HRXRD, and 1.20×1013 and 1.50×1013 cm−2 using in-plane strain values from room temperature PL band edge emission, respectively. Also, the calculated 2DEG concentrations were compared with the experimental outcomes using Hall-effect measurement based on van-der-Pauw geometry at 300 K. The experimental 2DEG concentrations were found to be 1.45×1013 and 2×1013 cm−2 for AlGaN/GaN and AlGaN/InGaN, respectively. The enhanced carrier concentrations from both analytical and experimental observations are attributed to the effect of “In” incorporation in the channel layer.

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Structural, morphological, and optical properties of AlGaN/GaN heterostructures with AlN buffer and interlayer

Cited by 40 publications

References 36 publications

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

On the profile of frequency dependent dielectric properties of (Ni/Au)/GaN/Al0.3Ga0.7N heterostructures

XRD vs Raman for InGaN/GaN Structures

Structural, optical, and transport properties of AlGaN/GaN and AlGaN/InGaN heterostructure on sapphire grown by plasma assisted molecular beam epitaxy

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