Effects of Nitridation Temperatures on Gallium Nitride Thin Films Formed on Silicon Substrates

2014 ◽  
Vol 895 ◽  
pp. 57-62
Author(s):  
Chee Yong Fong ◽  
Sha Shiong Ng ◽  
Fong Kwong Yam ◽  
Abu Hassan Haslan ◽  
Hassan Zainuriah
Keyword(s):  
Thin Films ◽  
Optimal Growth ◽  
Longitudinal Optical ◽  
Longitudinal Optical Phonon ◽  
Silicon Substrates ◽  
Phonon Modes ◽  
Si Substrates ◽  
Coating Method ◽  
Nitridation Temperature

In this article, GaN thin films were successfully grown onp-type silicon (p-Si) substrates with orientation (100) through spin coating method followed by nitridation in ammonia ambient at various temperatures (750 °C, 850 °C, and 950 °C). The morphology of the GaN thin films were performed by using field-emission scanning electron microscopy. The results showed that the grain size increases with increasing nitridation temperature from 750 °C to 950 °C. Optical analysis of the GaN thin films was performed using Fourier transform infrared spectroscopy. It was confirmed from the results that the reflectance intensity of the transverse optical and longitudinal optical phonon modes of wurtzite GaN increases with increasing nitridation temperature. All the measured results show that nitridation temperature plays a very important role in improving the quality of the GaN thin films. Finally, the results revealed that the 950 °C was the optimal growth nitridation temperature for synthesizing GaN thin film.

scholarly journals Growth Temperature Dependence of Sol-Gel Spin Coated Indium Nitride Thin Films

2019 ◽  
Vol 290 ◽  
pp. 153-159 ◽  
Author(s):  
Zhi Yin Lee ◽  
Sha Shiong Ng ◽  
Fong Kwong Yam ◽  
Zainuriah Hassan
Keyword(s):  
Thin Films ◽  
Growth Temperature ◽  
Indium Nitride ◽  
Sol Gel ◽  
Longitudinal Optical ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Reflectance Measurement ◽  
Ir Reflectance ◽  
Coating Method

The study highlights the effects of growth temperatures ranging from 500 to 650 °C on the properties of indium nitride (InN) thin films prepared by sol-gel spin coating method followed by nitridation, also, the growth mechanism was studied in depth. The findings revealed that the InN crystal growth was promoted at the growth temperature of 600 °C, by which the crystalline quality of the deposited thin films was improved and the densely packed InN grains were formed. However, thermal decomposition of InN was observed at increasing temperature to 650 °C. Apart from that, the infrared (IR) reflectance measurement shows the presence of transverse and longitudinal-optical phonon modes of wurtzite structure InN. These vibrational modes were found to be slightly shifted from the theoretical values as a result of the incorporation of oxygen contamination in the deposited thin films.

Effect of Cd Substitution on Structural and Optical Properties of Zn1-xCdxSe Thin Films

2021 ◽  
Vol 1039 ◽  
pp. 382-390
Author(s):  
Arej Kadhim ◽  
Mustafa Kadhim ◽  
Haslan Abu Hassan
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Longitudinal Optical ◽  
Raman Shift ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Elemental Ratios ◽  
X Ray ◽  
Cdse Thin Film ◽  
Yellow Region

In this research, Zn1-xCdxSe alloys (x from 0 to 1) were synthesized by solid-state microwave (SSM) method of producing thermally evaporated thin films. The cubic structure and the elemental ratios of the films were studied using X-ray diffraction, scanning electron microscopy, and energy dispersive X-ray spectroscopy. The optical characterizations of the as-deposited film in terms of the energy band gap (Eg), photoluminescence (PL), and Raman shift spectra were conducted at the room temperature. The Eg values for the thin films from ZnSe to CdSe were 3.4 to 1.7 eV, respectively. The PL orange emission for ZnSe thin film at 565 nm, whereas 590 nm in the yellow region for CdSe thin film. From Raman shift spectra, the two longitudinal-optical phonon modes (1LO and 2LO) at 240, and 490 cm-1 are assigned for the ZnSe and CdSe thin films.

scholarly journals Annealing-induced effects on structural and optical properties of Cd1−xZnxS thin films for optoelectronic applications

2015 ◽  
Vol 33 (4) ◽  
pp. 677-684 ◽  
Author(s):  
M. Zakria ◽  
Taj Muhammad Khan ◽  
Abbas Nasir ◽  
Arshad Mahmood
Keyword(s):  
Thin Films ◽  
Blue Shift ◽  
Ambient Air ◽  
Longitudinal Optical ◽  
Hexagonal Structure ◽  
Longitudinal Optical Phonon ◽  
X Ray Diffraction ◽  
Phonon Modes ◽  
Different Temperatures ◽  
Xrd Studies

AbstractCd1−xZnxS thin films of variable compositions (x = 0.2, 0.4, 0.6, 0.8) were deposited on glass at room temperature by thermal evaporation process. The prepared samples were annealed at two different temperatures (300 °C, 400 °C) for 1 hour in ambient air. The effects of post-annealing on the structural and optical characteristics were investigated using X-ray diffraction (XRD), spectrophotometry, and Raman spectroscopy (RS) methods. XRD studies suggested that the annealed and as-deposited samples belong to wurtzite structure for all Zn concentrations with a preferential orientation along (002) plane. Spectrophotometry analysis of the samples revealed that the energy band gap decreased with annealing temperature. RS investigated different phonon bands and crystalline phases. Two longitudinal optical phonon modes (1-LO, 2-LO) corresponding to monophase hexagonal structure were observed for all Cd1−xZnxS samples. The observed red-shift and anti-symmetrical nature of the 1-LO phonon mode can be associated with annealing, while the overall blue-shift, except for x ⩽ 0.6, was caused by the structural disorders in periodic Cd atomic sub-lattices and broken translational symmetry. The spectroscopic results were strengthened by the XRD studies and their results are consistent.

Raman Characterization of Doped 3C-SiC/Si for Different Silicon Substrates and C/Si Ratios

2010 ◽  
Vol 645-648 ◽  
pp. 255-258 ◽  
Author(s):  
Nicolò Piluso ◽  
Andrea Severino ◽  
Massimo Camarda ◽  
Ruggero Anzalone ◽  
Andrea Canino ◽  
...  
Keyword(s):  
Thin Films ◽  
Carrier Density ◽  
Gas Flow ◽  
Strong Relationship ◽  
Free Carrier ◽  
Silicon Substrates ◽  
Accurate Analysis ◽  
Si Substrates ◽  
Free Carrier Density ◽  
Longitudinal Optic Phonon

Raman microscopy has been used to study transport properties in hetero-epitaxial 3C-SiC/Si thin films. By an accurate analysis of the Longitudinal Optic phonon-plasmon coupled (LOPC) modes in n-type doped 3C-SiC films, free carrier density and mobility has been determined. A study of doped 3C-SiC reveals a strong relationship between the calculated free carrier density and both the C/Si ratio used during the epitaxial process and Silicon substrates orientation on which 3C-SiC thin films were grown (maintaining the N2 gas flow rate). The free carrier density obtained is in the range between 5x1016 cm-3 and 4x1018 cm-3. Epitaxial films grown on (111) Si substrates show a higher free carrier density and a lower dependence on C/Si ratios as compared to films grown on (100) Si substrates.

In‐Situ Fabrication of YBa2Cu3O7‐x Superconducting Thin Films Directly on Silicon Substrates with Tc0 > 77K

1989 ◽  
Vol 169 ◽  
Author(s):  
C. B. Lee ◽  
R. K. Singh ◽  
S. Sharan ◽  
A. K. Singh ◽  
P. Tiwari ◽  
...  
Keyword(s):  
Thin Films ◽  
Laser Pulses ◽  
Superconducting Film ◽  
Laser Evaporation ◽  
Silicon Substrates ◽  
Superconducting Thin Films ◽  
Si Substrates ◽  
In Situ Fabrication ◽  
Substrate Temperatures

AbstractWe report in‐situ fabrication of c‐axis textured YBa2Cu3O7‐x superconducting thin films with Tco > 77K on unbuffered silicon substrates by the biased pulsed laser evaporation (PLE) technique in the temperature range of 550‐650°C. At substrate temperatures below 550°C, no c‐axis texturing of the superconducting film was observed. The YBa2Cu3O7‐x superconducting films were fabricated by ablating a bulk YBa2Cu3O7 target by a XeCl excimer laser (λ = 308 nm, τ = 45 × 10‐9 sec) in a chamber maintained at an oxygen pressure of 0.2 torr . The thickness of the films was varied from 0.3 to 0.5 nm depending on the number of laser pulses. Extensive diffusion was observed in thin films deposited at substrate temperatures above 550°C. However, microstructurally, with increase in the substrate temperature the films exhibited larger grain size and greater degree of c‐axis texturing (measured by the ratio of the (005) and (110) X‐ray diffraction peaks). This was found to give rise to better superconducting properties with Tco exceeding 77 K for YBa2Cu3O7‐x films deposited on Si substrates at 650°C.

Electron-Phonon Scattering in GaN/AlN and GaAs/AlAs Quantum Wells

1997 ◽  
Vol 482 ◽  
Author(s):  
T. F. Forbang ◽  
C. R. McIntyre
Keyword(s):  
Quantum Wells ◽  
Optical Phonon ◽  
Phonon Spectrum ◽  
Phonon Scattering ◽  
Relaxation Times ◽  
Longitudinal Optical ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Optical Phonon Scattering ◽  
Electron Phonon Scattering

AbstractWe have studied the effects on the phonon spectrum and on the electron-longitudinal optical phonon scattering in GaN/AlN and GaAs/AlAs quantum wells. Phonon modes and potentials have been calculated for both systems. Results for emission due to electroninterface phonons interactions are presented. We will discuss the implications for relaxation times and electron mobility due to modified LO-phonon scattering in both systems.

Nondestructive Characterizations of Au-Catalyzed GaAs Nanowires on GaAs(111)B Substrates via Identifications of 1st Order Optical Phonon Modes Using μ-Raman Spectroscopy

2020 ◽  
Vol 20 (7) ◽  
pp. 4358-4363
Author(s):  
Jeung Hun Park ◽  
Richard S. Kim ◽  
Se-Jeong Park ◽  
Gye-Choon Park ◽  
Choong-Heui Chung
Keyword(s):  
Raman Spectroscopy ◽  
Dose Rate ◽  
Raman Spectra ◽  
Optical Phonon ◽  
Longitudinal Optical ◽  
Transverse Optical ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
Gaas Nanowires ◽  
Beam Dose

We report the relation between the catalyst patterning conditions and the intensity of the 1st order Raman active modes in Au-catalyzed GaAs nanowire bundles. We fabricated e-beam lithographically Au-patterned GaAs(111)B substrates by varying the patterning conditions (e-beam dose rate, dot-size and interdot-spacings), and grew GaAs nanowires via vapor–liquid–solid process using a solid-source molecular beam epitaxy. To understand the effects of the substrate preparation conditions and resulting morphologies on the optical characteristics of 1st order transverse optical and longitudinal optical phonon modes of GaAs, we characterized the nanowire bundles using complementary μ-Raman spectroscopy and scanning electron microscopy as a function of the e-beam dose rate (145–595 μC/cm2), inter-dot spacing (100 and 150 nm) and pattern size (100 and 150 nm). Ensembles of single crystalline GaAs nanowires covered with different Au-thickness exhibit a downshift and asymmetric broadening of the 1st order transverse optical and longitudinal optical phonon peaks relative to GaAs bulk modes. We also showed that the sensitivity of a downshift and broadening of Raman spectra are directly related to morphological and surface coverage variations in as-grown nanowires. We observed clear increases of the transverse optical and longitudinal optical intensity as well as the relatively higher peak shift and broadening of Raman spectra from the 100 nm patterning in response to the dose rate change. Strong dependence of Raman spectra of the nanowire bundles on the e-beam dose rate changes are attributed to the variations in spatial density, size, shape and random growth orientation of the wires. We have shown that the identification of the changes in GaAs longitudinal optical and Arsenic anti-site peaks is good indicators to characterize the quality of as-grown GaAs nanowires. Our finding confirms the utilization of Raman spectroscopy as a powerful tool for characterizing chemical, structural, and morphological information of as-grown nanowires within the supporting substrate.

Admittance and Photoadmittance Spectroscopy of Zinc Oxide Layers Grown on p-Si Substrates by Spin Coating Method

2013 ◽  
Vol 200 ◽  
pp. 27-32
Author(s):  
Pawel Popielarski ◽  
Waclaw Bala ◽  
Kazimierz Paprocki
Keyword(s):  
Thin Films ◽  
Temperature Dependence ◽  
Dielectric Response ◽  
Ac Conductivity ◽  
Signal Amplitude ◽  
Zno Thin Films ◽  
Si Substrates ◽  
Universal Power Law ◽  
Coating Method ◽  
Different Temperatures

In this work, the dielectric response of ZnO thin films has been studied over a temperature range of 200 K - 550 K. The dielectric response of polycrystalline ZnO thin films in the frequency domain was measured from 42 Hz - to 5 MHz with a small AC signal amplitude at different temperatures. Influence of the light on conductivity has been also investigated. A universal power law relation was brought into picture to explain the frequency dependence of AC conductivity. The temperature dependence of AC conductivity was analyzed in detail. The activation energy obtained from the temperature dependence of AC conductivity was attributed to the shallow trap-controlled space charge conduction in the bulk of the sample.

ESR AND RAMAN STUDIES OF CHEMICAL BATH DEPOSITED CdS : Ni FILMS

2008 ◽  
Vol 22 (22) ◽  
pp. 2113-2121 ◽  
Author(s):  
U. INTATHA ◽  
S. EITSSAYEAM ◽  
K. PENGPAT ◽  
N. UDOMKAN ◽  
P. LIMSUWAN ◽  
...  
Keyword(s):  
Longitudinal Optical ◽  
Esr Spectra ◽  
Band Gaps ◽  
Longitudinal Optical Phonon ◽  
Phonon Modes ◽  
X Ray ◽  
Glass Substrates ◽  
Spin Resonance ◽  
Xrd Patterns ◽  
Cubic Cds

The CdS : Ni films were fabricated on glass substrates by chemical bath deposition method (CBD), where Ni concentrations are 0%, 10%, 20%, 30% and 40%. X-ray diffractometry (XRD), Raman spectroscopy and electron spin resonance (ESR) were employed to study the film structures. The XRD patterns revealed the presence of cubic CdS and trace of NiS . The Raman spectra were observed at 300 and 600 cm-1, corresponding to the first and second orders of the longitudinal optical phonon modes. Both results confirm that slightly lower order of crystallinity of CdS : Ni was found at the higher concentration of Ni . The ESR spectra showed the presence of F-type defects in CdS : Ni films. The band gaps of the samples were found to increase with the increase of Ni concentration.

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