Growth of GaN Nanostructures On Graphene A vinash Patsha Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India Kishore K. Madapu Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India P.Sahoo Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India S. Dhara Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India dhara@igcar.gov.in A. K. Tyagi Surface and Nanoscience Division, Indira Gandhi Centre for Atomic Research, Kalpakkam-603102, India Abstract-GaN nanostructures with different morphologies are grown on few layer graphene (FLG) as template, using chemical- vapor-deposition technique in a self catalytic process using the large surface energy of graphene. Raman and photoluminescence studies reveal wurtzite GaN phase. Morphologies of these nanostructures varied depending on the number of layers in each template. Photoluminescence study reveals that growth occurs without deterioration of FLG layers and no incorporation of carbon in GaN nanostructures Keywords- gaum nitride; GaN; graphene; nanostructures; Raman spectroscopy; photoluminescence I. INTRODUCTION Among all inorganic compound semiconductors, GaN has special attention owing to its optical ansparency being a wide material band gap, high caier mobility, high melting point, electrical breakdown field, and optoeleconic electronic properties [1,2]. Despite tremendous advancement in the synthesis of GaN nanosucture, efforts are still being made worldwide to grow new structures and to study their properties. Recently, there is growing interest in the integration of ID/2D semiconducting nanosucturelgraphene hetero-nanosuctures [3]. This system can offer a unique opportunity to study the physics at interfaces between semiconducting nanosuctures and graphene. In fact, efforts are being made to study the growth of semiconducting nanocrystals on graphene layers [4]. Graphene is a monolayer of s l-bonded carbon atoms aanged in a hexagonal, honeycomb lattice and it has been atacting great interest because of its distinctive band sucture and physical properties [5]. Here, we report the direct growth of GaN nanosuctures with different morphologies on graphene layers as patteed templates. Vibrational and optical properties are studied for phase analysis as well as defect studies in these nanostructures. 978-1-4673-0074-2/11/$26.00 @2011 IEEE 553 II. EXPERIMENTAL DETAILS Growth of GaN/FLG hetero-nanosuctures was performed using conventional chemical vapor deposition (CVD) technique within the hot zone of ace, described elsewhere [6]. Commercially available few layer graphene (FLG) powder was nctionalized with COOH- group by treatment of piranha solution (9: 1 of H2S04 and H202) [7]. The nctionalization helped for the dispersion of FLG when dissolved in deionized water. Piranha eatment made it contamination ee also. Highly diluted dispersed FLG solution was then ansfeed onto the crystalline (c-)Si (100) subsates, for making patteed templates; using drop cast method. Finally, the patterened template was dried. We must state, here that the numbers of graphene layers in the FLG templates were different (details in the results and discussion). These subsates were kept on a high pure alumina boat along with source material and, subsequently, were introduced in to the quartz tube of horizontal ace. Ga (99.999%) metal used as a source material and reactive NH3 was used as precursor at a constant flow rate of 30 sccm at 850 oC for 2 hrs. Mohological studies were performed using field-emission scanning elecon microscope (FESEM; Zeiss-SUPRA 40). Micro-Raman specoscopy (inVia; Reinshaw, UK) with 514.5  excitation of an Ar+ laser using grating of 1800 grimm and thermoelecic cooled CCD detector for studying vibration properties. The optical properties of the samples were studied using photoluminescence (PL) specoscopy with excitation of 325  of He-Cd laser III. SULTS AND DISCUSSION Figure 1 shows the FESEM images of GaN nanostructures, with various mohologies, namely, nanoflowers (Fig. la), (high magnification image shown in Fig. 1b), nanothreads (Fig.