Search results for "Vapour phase epitaxy"
showing 6 items of 76 documents
Ex situ investigations of MOCVD-grown gallium nitride nanowires using reflection high energy electron diffraction
2011
Vertically oriented nanowires (NWs) of single-crystalline wurtzite GaN have been fabricated on sapphire substrates, via metal organic chemical vapor deposition (MOCVD). We present ex situ investigations on orientation and structure of grown GaN nanowires on GaN(0001) surface using reflection high energy electron diffraction (RHEED). Both ordered and randomly oriented GaN crystalline structures have been detected.
Optical and structural studies of GaN 3D structures selectively grown by MOCVD
2004
Abstract This paper presents preliminary results on the selective growth of three-dimensional (3D) micrometric metallic structures by the MOCVD technique. The 3D structure growth occurs by simply feeding the reactor gas phase with a conventional flow of metal-organic (MO), trimethyl-gallium (TMGa) molecules. Selectivity occurs at the substrate surface in which MO species travel tens of micrometers in order to build up the 3D structure. After the growth, these structures are nitrided in order to give GaN-related optical visible emission. Optical emission results are presented and discussed in this paper. Both 3D structures deposition and annealing experiments can be extended to other III–V m…
Morphology transitions in ZnO nanorods grown by MOCVD
2012
Morphology transitions (nanorods–nanowalls and nanorods–nanotubes-layer) were induced in the growth of ZnO nanostructures by metal organic chemical vapor deposition (MOCVD) on c-sapphire, using helium as carrier gas, and dimethylzinc–triethylamine and nitrous oxide as zinc and oxygen sources, respectively. A systematic study of the influence of the VI/II ratio and precursor flow-rates on the morphology of ZnO nanorod arrays has been carried out, taking advantage of the ability of MOCVD to individually control the precursor partial pressures. Growth mechanisms are discussed to understand the evolution of the nanostructures morphology for different growth conditions. In particular, the influe…
Low-pressure-MOCVD LaMnO3±δ very thin films on YSZ (100) optimized for studies of the triple phase boundary
2000
Abstract This paper deals with the preparation of LaMnO 3± δ (LM) layers by low pressure-metal organic chemical vapor deposition (LP-MOCVD) using La(tmhd) 3 and Mn(acac) 3 as organometallic precursors. By thermogravimetric analysis, these precursors were found to be suitable for LP-MOCVD in a well-defined range of total pressure and temperature of sublimation. The activation energies of the sublimation process were found to be independent of the pressure within the appropriate range (0.06–3 kPa) and their values were 177 and 100.5 kJ mol −1 for La(tmhd) 3 and Mn(acac) 3 , respectively. LM layers of various thickness ranging between a few and a few hundred nanometers with a controlled La/Mn …
MOCVD deposition of YSZ on stainless steels
2003
Abstract Yttria stabilized zirconia was deposited on stainless steel using the metal–organic chemical vapor deposition (MOCVD) technique, from β-diketonate precursors. The variation of the evaporation temperatures of yttrium and zirconium precursor allowed to control the level of Y within the film. Over the temperature range 125–150 °C, the Y content increased from 2.5 to 17.6 at.%. X-ray diffraction (XRD) analyses evidenced tetragonal phase of zirconia when the Y content was below 8 at.%, and cubic phase for higher concentration. Sputtered neutral mass spectrometry (SNMS) profiles confirmed that the control and stability of Y precursor temperature were of major importance to guarantee the …
Synchrotron radiation multiple diffraction study of Al0.304Ga0.172In0.524As MOVPE grown onto InP(001)
1997
Synchrotron radiation multiple diffraction in Renninger scanning (RS) geometry is used to characterise an Al0.304Ga0.172In0.524 As hetero-epitaxial layer MOVPE grown onto InP(001). (006) RS data for bulk, InP substrate and the quaternary layer were obtained using a new experimental set-up on station 7.6 at the Daresbury synchrotron radiation source. Examination of the multiple diffraction peak profiles reveal the epitaxial layers to have a higher mosaic spread than the underlying substrate materials. Measurements of the layer parallel lattice parameter a∥ = 5.8755 ± 0.003 A, as deduced from the tetragonal distortion measured at the 6-beam case in the layer RS, agrees very well with that obt…