Controlled nucleation and growth of nanostructures by employing surface modified GaN based layers/heterostructures as bottom layer

Abstract

Controlled nucleation and growth of Zinc oxide nanorods is achieved on GaN, etched GaN and AlGaN/GaN heterostructure bottom layers grown by a metal organic chemical vapour deposition technique. The effects of the bottom crystalline layers on the structural, morphological and optical properties of the as grown ZnO nanorods have been investigated by high-resolution X-ray diffraction, scanning electron microscopy, photoluminescence and Raman measurements. HRXRD (0002) reciprocal-space mapping (RSMs) studies were performed on GaN and AlGaN/GaN layers before and after the growth of ZnO nanostructures to investigate the impact of strain upon the ZnO layer grown on GaN layers and AlGaN/GaN heterostructures. Raman intensity mapping shows the densely nucleated hexagonal pit like structures for the etched GaN layer, providing an enhanced surface area for primary nucleation suggesting that the growth species prefer to condense on locations with maximum binding energy. The increase in nucleation density for etched GaN layers also result in dense nanorods which exhibit better excitonic emission. Our studies suggest that ZnO nanostructures with improved optical and structural properties can be grown on etched-GaN as well as AlGaN/GaN heterostructures as the bottom layer. It is interesting to observe that the bottom GaN layer can be easily employed to determine the optical quality of ZnO layer. Experimental detailsGaN based epitaxial layers and heterostructures were deposited on c-sapphire substrates by metal organic chemical vapour deposition (MOCVD), Aixtron 200/4 RF-S system. Trimethyl

Nitridation effect of the α-Al2O3 substrates on the quality of the GaN films grown by pulsed laser deposition

“…Nowadays, GaN and its related III-nitrides have generated a great deal of interest due to their superior properties, which make them viable for the applications such as light-emitting diodes, laser diodes, eld effect transistors, and photo-detectors. [1][2][3][4][5] As usual, GaN lms are grown by metal-organic chemical vapor deposition (MOCVD). [6][7][8] However, it requires a high growth temperature, which leads to high consumptions in both power and cost.…”

Abrasive Free Chemical Mechanical Planarization of Semi-Polar (11–22) GaN: Effect on Structural and Surface Properties and Subsequent Homoepitaxial Growth

“…29 It has been reported that chemical reaction/etching by CMP of GaN surface can result in exposing the dislocations created during the original growth process, which are covered during the re-growth process. 15,22,30,31 Recently, Li et al reported the in-plane stress along m-axis is two orders of magnitude higher than that along c-axis on the overgrown semi-polar (11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22) GaN epilayer. 29 They have explained that this is due to the dissimilar growth rate and lattice mismatch.…”

Dome-shaped patterned sapphire substrate with optimized curvature to enhance the efficacy of light emitting diodes

“…Ever since high-efficiency p-GaN doping was successfully achieved by Akasaki, 1 GaN-based semiconductors have attracted intense interest due to wide applications for blue and white light emitting diodes (LEDs). [2][3][4] To date, LEDs' luminous efficiency has been much higher than that of lament lamps. However, to meet the market demand for high power lighting and make full use of LEDs' superiorities, luminous efficiency for LEDs still needs indispensable improvement.…”