Sonochemical growth technique is based upon the chemical effect of ultrasound on chemical reactions. This process is carried out at an ambient atmosphere without the need for a complex experimental set up and additional heating. This method is of significant importance because of it's vital application in various fields. ZnO nanorods were grown on glass substrates without any additional heat or surfactance by sonochemical growth technique. The grown nanostructures were characterized by Raman spectroscopy, scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). Sonochemically grown ZnO nanorod networks were characterized for their antibacterial properties toward B.subtilis. These structures were also characterized for their CO sensing properties and photovoltaic performances for dye sensitized solar cell (DSSC) application. All material characterization and device performances suggest that sonochemsitry can be utilized as an alternative growth method for 1D ZnO nanostructures.
The dependency of the structural and optoelectronic properties of InN thin films grown by high-pressure chemical
vapor deposition technique on the group V/III molar precursor ratio has been studied. X-ray diffraction, Raman
spectroscopy, and IR reflectance spectroscopy have been utilized to study local- and long-range structural ordering as
well as optoelectronic properties of the InN epilayers grown on crystalline sapphire substrates. The investigated InN
epilayers were grown with group V/III molar precursor ratio varying from 900 to 3600, while all other growth
parameters were kept constant. For a group V/III precursor ratio of 2400, the full width-half maximum of the Raman
E2(high) mode and XRD (0002) Bragg reflex exhibit minimums of 7.53 cm⁻¹ and 210 arcsec, respectively, with
maximized grain size and reduced in-plane strain effect. FTIR data analysis reveals a growth rate of 120 nm/hr, a carrier
mobility of 1020 cm²V⁻¹s⁻¹, and a free carrier concentration of 1.7×1018 cm⁻³ for a V/III ratio of 2400. The Raman
analysis indicate that non-polar E2(high) mode position remains unaffected from a changing V/III ratio; whereas, polar
A1(LO) mode position significantly changes with changing V/III ratio. Optical analysis also suggests that LO-phonon
correlates with free carrier concentration (ne) and TO-phonon correlates with free carrier mobility (μ) in the InN
The influence of structural and optoelectronic properties of InN epilayers on the duration of initial nucleation
has been studied. High pressure chemical vapor deposition (HPCVD) has been utilized to deposit InN epilayers on
GaN/sapphire (0001) templates at a reactor pressure of 15 bar. The initial nucleation period was varied between 10 s and 60 s, leaving all other growth parameters constant. The structural properties of the grown samples have been investigated by X-ray diffraction (XRD) spectroscopy and Raman spectroscopy. The optoelectronic properties were analyzed by Fourier transform infra-red (FTIR) spectroscopy. The layer thickness, free carrier concentration and void fraction were obtained by simulating IR spectra, using multi-layer stack model for epilayers and Lorentz-Drude model for dielectric function. Raman, X-ray diffraction (XRD) and void fraction calculation results suggest that the optimum nucleation time is between 10 - 20 s. However, simulation results revealed that the free carrier concentration of the bulk layer does not show any significant dependency on the duration of initial nucleation.
Results on the achievable growth temperature as a function of the reactor pressure for the growth of InN by high-pressure CVD are presented. As the reactor pressure was increased from 1 bar to 19 bar, the optimal growth temperature raised from 759°C to 876°C, an increase of 6.6 °C/bar. The InN layers were grown in a horizontal flow channel reactor, using a pulsed precursor injection scheme. The structural and optical properties of the epilayers have been investigated by Raman spectroscopy, X-ray diffraction, and IR reflectance spectroscopy.
The optical and structural properties of InN layers grown by 'High Pressure Chemical Vapor
Deposition' (HPCVD) using a pulsed precursor approach have been studied. The study focuses on
the effect of ammonia precursor exposure time and magnitude on the InN layer quality. The samples
have been analyzed by X-ray diffraction, Raman scattering, infra red reflectance spectroscopy and
photoluminescence spectroscopy. Raman measurements and X-ray diffraction showed the grown
layers to be single phase InN of high crystalline quality. The E2(high) Raman mode showed
FWHM's as small as 9.2 cm-1. The FWHM's of the InN(0002) X-ray Bragg reflex in the 2Θ-Ω-
scans were around 350 arcsec, with rocking curve values as low as 1152 arcsec Photoluminescence
features have been observed down to 0.7 eV, where the low energy cutoff might be due to the
detector limitation. The analysis of the IR reflectance spectra shows that the free carrier
concentrations are as low as as 3.3•1018 cm-3 for InN layers grown on sapphire substrates.