Micro-Raman spectroscopy of a single freestanding GaN nanorod grown by molecular beam epitaxy

Herein, we report the self-aligned growth of GaN nanorods on different orientations of sapphire like c-, a-, rand m-plane substrates by hydride vapor phase epitaxy. Vertical c-axis orientation of GaN NRs is obtained on c-plane [0001] and a-plane 11 20 ½ sapphire and a skew or inclined NRs on r-plane, and inclined intertwined but self-aligned NR array was formed on m-plane sapphire. GaN (002) and (004) peaks were obtained on c-and a-plane sapphire, whereas (110), (103), and (103) only were observed on r-and mplanes, respectively. In the case of r-and m-plane-grown GaN, A 1 transverse optical mode is dominant, and the A 1 longitudinal optical mode is suppressed. Conversely, in the case of c-and a-plane, it is reversed. The probable reason is the optical mode vibrations difference along the differently inclined NRs surfaces. In addition, the specimen exhibits surface optical modes too. The optical behavior of GaN NR on m-sapphire shows an intensity variation when measured in different angular rotations of the specimen by photoluminescence which is because of the higher area of excitation in the case of axial surfaces and lower area of excitation in radial surface. Their epitaxial crystallographic relationship with the substrates and the reasons for the self-aligned orientations are discussed. The anomalies found in the optical behavior are attributed to Raman antenna effect and so on. The self-aligned intertwined GaN NRs find suitable applications in polarizer.

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“…4. Sharp E 2 high modes in all of the NRs confirm the high crystalline quality of the NRs grown by HVPE [24,25].…”

Section: Optical Propertiessupporting

confidence: 63%

HVPE growth of self-aligned GaN nanorods on c-plane, a-plane, r-plane, and m-plane sapphire wafers

et al. 2015

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“…The process makes the intensity of the SO mode comparable to that of the other phonons. SO mode in a single GaN nanowire grown by molecular beam epitaxy has also been reported by Hsiao and co-workers (Hsiao et al, 2007) during angle dependent Raman spectroscopy measurement with the z axis pointing along the crystallographic c axis of the rod. The direction of different angles between the laser polarization and the rod length (c axis) are shown in figure 9 (a).…”

Section: Gan Nanowiresmentioning

confidence: 81%

Section: Gan Nanowiresmentioning

confidence: 99%

Surface Optical Modes in Semiconductor Nanowires

Sahoo¹,

Tyagi²,

Raj³

et al. 2011

Nanowires - Implementations and Applications

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“…A detailed description of the MBE with ultra-high vacuum (UHV) system, K cells, a quartz crystal thickness monitor, low energy electron diffraction (LEED) camera, heater can be found in many articles. [11][12][13][14]30,31 Briefly, the deposition UHV chamber was first pumped down to base pressure of 10 −10 torr, while substrate was annealed at 900 • C for 30-60 minutes in order to remove most impurity or residue gas. Before Si substrates were placed into the chamber, they were ultrasonically washed in the methanol solution followed by standard cleaning.…”

Section: Synthesis and Basic Characterization Of Gan Thin Filmsmentioning

confidence: 99%

“…Higher electron mobility and electron saturation velocity allow for higher frequency of operation, and fast responsivity. 3,4 To date, the synthesis of different types of GaN materials have been performed by using various technical routes, including pulsed laser deposition techniques, 5 electrochemical techniques, 6 hot filament chemical vapor deposition (HFCVD), 7 plasma enhanced CVD, 8 sputtering method, 9 spin coating method, 10 and molecular beam epitaxy (MBE), [11][12][13][14] among others.…”

Section: Introductionmentioning

confidence: 99%

Fabrications and application of single crystalline GaN for high-performance deep UV photodetectors

et al. 2016

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High-quality single crystalline Gallium Nitride (GaN) semiconductor has been synthesized using molecule beam epitaxy (MBE) technique for development of high-performance deep ultraviolet (UV) photodetectors. Thickness of the films was estimated by using surface profile meter and scanning electron microscope. Electronic states and elemental composition of the films were obtained using Raman scattering spectroscopy. The orientation, crystal structure and phase purity of the films were examined using a Siemens x-ray diffractometer radiation. The surface microstructure was studied using high resolution scanning electron microscopy (SEM). Two types of metal pairs: Al-Al, Al-Cu or Cu-Cu were used for interdigital electrodes on GaN film in order to examine the Schottky properties of the GaN based photodetector. The characterizations of the fabricated prototype include the stability, responsivity, response and recovery times. Typical time dependent photoresponsivity by switching different UV light source on and off five times for each 240 seconds at a bias of 2V, respectively, have been obtained. The detector appears to be highly sensitive to various UV wavelengths of light with very stable baseline and repeatability. The obtained photoresponsivity was up to 354 mA/W at the bias 2V. Higher photoresponsivity could be obtained if higher bias was applied but it would unavoidably result in a higher dark current. Thermal effect on the fabricated GaN based prototype was discussed.

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Micro-Raman spectroscopy of a single freestanding GaN nanorod grown by molecular beam epitaxy

Cited by 58 publications

References 21 publications

HVPE growth of self-aligned GaN nanorods on c-plane, a-plane, r-plane, and m-plane sapphire wafers

HVPE growth of self-aligned GaN nanorods on c-plane, a-plane, r-plane, and m-plane sapphire wafers

Surface Optical Modes in Semiconductor Nanowires

Fabrications and application of single crystalline GaN for high-performance deep UV photodetectors

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