Optical Properties of Novel GaN 3D Structures Grown by Metal-Organic Chemical Vapor Deposition (MOCVD)

Abstract

Optical properties of novel micrometer-size Ga and GaN three-dimensional structures obtained by the metal-organic chemical vapour deposition (MOCVD) technique are presented in this letter. These structures are obtained as metallic three dimensions (3D) micrometer-size objects on an appropriate substrate by metalorganic (TMGa) pyrolisis and then GaN transformed on annealing under NH3 atmosphere at 650–750°C. These 3D GaN structures are analysed by optical means, using two-photon excitation (800 nm) and by UV Hg lamp fluorescent spectroscopy techniques, adapted to two-optical-microscopes apparatus. Very intense and blue/yellow light emission is observed from these 3D structures under 800 nm two-photon laser excitation and under UV Hg lamp excitation.

MOVPE growth of Ga 3D structures for fabrication of GaN materials

“…Since elemental/structural studies are needed to understand the 3D Ga deposition and GaN formation, catalytic effects cannot be discarded to explain the present results. Optical spectroscopy shows that the nitrided 3D structures' emission is in the visible 400-600 nm range [15]. Our optical spectroscopy experimental set-up is similar to the one reported by Tachibana et al [17].…”

“…It should be noted that, in the same way, 3D metallic structures can be obtained for metals such as Ga, Al and In, as well their mixed alloys, and it will be proposed in a forthcoming paper. They could be also submitted to the same nitridation process in order to get GaN-like structures [15]. 1 A GaN-like structure is obtained by annealing under NH 3 at 650-750 C, that is far below the temperature used to get GaN structures for high-performance visible light devices applications (around 1000 C for the MOVPE technique) [3].…”

Optical and structural studies of GaN 3D structures selectively grown by MOCVD

“…The growth of gallium 3D structures is performed in a MOCVD system between 650 and 750 1C with a reactor pressure in the 100-760 Torr range, using TMGa as a Ga source and nitrogen as a carrier gas [10,11]. We should stress that these 3D gallium deposits are performed naturally by MOCVD, without any other artifact.…”

“…These 3D selective GaN structures were analyzed by optical means, using two-photon excitation (2PH, 800 nm) and by UV Hg lamp fluorescent spectroscopy techniques (360 nm), adapted to two optical microscopes apparatus [4, [11][12][13][14][15]. Briefly, the 2PH technique can analyze small surfaces down to 19 Â 19 mm 2 and the FL technique can analyze a spot surface diameter of about 500 nm.…”

“…In order to do so, optical microscopy (OM), scanning electron microscopy (SEM), cathodoluminescence (CL), twophoton excitation (2PH), and fluorescence (FL) techniques are employed in order to characterize these 3D structures. The 3D structure chemical composition and crystallographic analysis have already been previously reported [10,11]. The room temperature (RT) 2PH and FL experimental details are described elsewhere and are performed under optical microscopic conditions [4,[11][12][13][14][15].…”