scholarly journals Synthesis of Serrated GaN Nanowires for Hydrogen Gas Sensors Applications by Plasma-Assisted Vapor Phase Deposition Method

2017 ◽  
Vol 7 (3) ◽  
Author(s):  
Mahdi Gholampour
Keyword(s):  
Band Gap ◽  
Vapor Phase ◽  
Gas Sensors ◽  
Wide Band ◽  
Band Gap Energy ◽  
Hexagonal Structure ◽  
Hydrogen Gas ◽  
Wide Band Gap ◽  
Vapor Phase Deposition ◽  
Hydrogen Gas Sensors

Nowadays, the semiconductor nanowires (NWs) typically used in hydrogen gas sensors. Gallium nitride (GaN) with a wide band gap of 3.4 eV, is one of the best semiconductors for this function. NWs surface roughness have important role in gas sensors performance. In this research, GaN NWs have been synthesized on Si substrate by plasma-assisted vapor phase deposition at different deposition time, without using any catalyst. The precursors were gallium (Ga) metal and nitrogen (N) plasma. The GaN NWs were characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy )FE-SEM(, photoluminescence (PL) and Raman Spectroscopy. The results indicate the serrated morphology for hexagonal structure of GaN NWs. The band gap energy of GaN NWs was obtained about 3.41 eV. The Raman results show two Raman active optical phonons at 563 cm-1 and 720 cm-1 due to E2(high) and A1(LO), respectively and indicates a good crystallinity of the NWs with the presence of defects in the crystal lattice.

scholarly journals Development of β-Ga2O3 layers growth on sapphire substrates employing modeling of precursors ratio in halide vapor phase epitaxy reactor

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Galia Pozina ◽  
Chih-Wei Hsu ◽  
Natalia Abrikossova ◽  
Mikhail A. Kaliteevski ◽  
Carl Hemmingsson
Keyword(s):  
Band Gap ◽  
Vapor Phase ◽  
Wide Band ◽  
Band Gap Energy ◽  
Vapor Phase Epitaxy ◽  
Structural Quality ◽  
Wide Band Gap ◽  
Vacancy Defects ◽  
Sapphire Substrates ◽  
Efficient Power

AbstractGallium oxide is a promising semiconductor with great potential for efficient power electronics due to its ultra-wide band gap and high breakdown electric field. Optimization of halide vapor phase epitaxy growth of heteroepitaxial $$\upbeta$$ β -Ga2O3 layers is demonstrated using a simulation model to predict the distribution of the ratio of gallium to oxygen precursors inside the reactor chamber. The best structural quality is obtained for layers grown at 825–850 °C and with a III/VI precursor ratio of 0.2. Although the structural and optical properties are similar, the surface morphology is more deteriorated for the $$\upbeta$$ β -Ga2O3 layers grown on 5 degree off-axis sapphire substrates compared to on-axis samples even for optimized process parameters. Cathodoluminescence with a peak at 3.3 eV is typical for unintentionally doped n-type $$\upbeta$$ β -Ga2O3 and shows the appearance of additional emissions in blue and green region at ~ 3.0, ~ 2.8, ~ 2.6 and ~ 2.4 eV, especially when the growth temperatures is lowered to 800–825 °C. Estimation of the band gap energy to ~ 4.65 eV from absorption indicates a high density of vacancy defects.

Alternating 2,7- and 3,6-linked carbazole copolymers as wide band gap energy transfer donors

2009 ◽  
Vol 517 (9) ◽  
pp. 2840-2844 ◽  
Author(s):  
David F. Pickup ◽  
Hunan Yi ◽  
Harismah Kun ◽  
Ahmed Iraqi ◽  
Mathew Stevenson ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Band Gap ◽  
Wide Band ◽  
Band Gap Energy ◽  
Wide Band Gap ◽  
Gap Energy

scholarly journals PERFORMANCE EVALUATION OF ZNO DOPED DIDYMIUM NANO POWDER SAMPLES

2015 ◽  
pp. 202-205
Author(s):  
MANISH SHARMA ◽  
R.P. GAIROLA
Keyword(s):  
Band Gap ◽  
Sol Gel ◽  
Wide Band ◽  
Hexagonal Structure ◽  
Major Constituent ◽  
Homogeneous Distribution ◽  
Wide Band Gap ◽  
Light Emitting Devices ◽  
Powder Samples ◽  
P Type

In the recent years, much attention has been focused on wide band gap semiconductors materials because of their excellent potential for blue light emitting devices, short-wavelength laser diodes and detectors in UV-blue spectral region. The wide band gap ZnO is gaining much importance for the possible application due to the capability of ultraviolet lasing at room temperature and possibilities to engineer the band gap for further use. In order to attain the potential offered by ZnO, both high-quality n-and p-type ZnO are essential. In this work we synthese the ZnO nanopowder by Sol–gel method & after that the ZnO is doped with rare earth material didymium. Didymium is a naturally occurring element with major constituent Nd and Pr and is used in many applications. The FTIR, SEM and EDX characterization techniques are applied to study the sample & it has been found that the formation of pure phase of ZnO having wurtzite hexagonal structure occurs at 1%, But at higher concentration of Di (3%, 5%) the system shows mixed phase. Moreover SEM shows that the Di doped ZnO has well ordered morphology, has low aggregation and homogeneous distribution of particle size. Note that the synthesized system is also having band gap of 3.24 eV which is comparable with the standard value.

scholarly journals Ti Alloyed α-Ga2O3: Route towards Wide Band Gap Engineering

Micromachines ◽  
2020 ◽  
Vol 11 (12) ◽  
pp. 1128
Author(s):  
Armin Barthel ◽  
Joseph Roberts ◽  
Mari Napari ◽  
Martin Frentrup ◽  
Tahmida Huq ◽  
...  
Keyword(s):  
Band Gap ◽  
Wide Band ◽  
Atomic Layer ◽  
Band Gap Energy ◽  
Wide Band Gap ◽  
Band Gap Engineering ◽  
Layer Deposition ◽  
Solar Blind ◽  
High Band

The suitability of Ti as a band gap modifier for α-Ga2O3 was investigated, taking advantage of the isostructural α phases and high band gap difference between Ti2O3 and Ga2O3. Films of (Ti,Ga)2O3 were synthesized by atomic layer deposition on sapphire substrates, and characterized to determine how crystallinity and band gap vary with composition for this alloy. We report the deposition of high quality α-(TixGa1−x)2O3 films with x = 3.7%. For greater compositions the crystalline quality of the films degrades rapidly, where the corundum phase is maintained in films up to x = 5.3%, and films containing greater Ti fractions being amorphous. Over the range of achieved corundum phase films, that is 0% ≤ x ≤ 5.3%, the band gap energy varies by ∼270 meV. The ability to maintain a crystalline phase at low fractions of Ti, accompanied by a modification in band gap, shows promising prospects for band gap engineering and the development of wavelength specific solar-blind photodetectors based on α-Ga2O3.

Highly Conductive and Wide Band GaP Microcrystalline Silicon Films Prepared by Photochemical Vapor Deposition and Applications to Devices

1985 ◽  
Vol 49 ◽  
Author(s):  
S. Nishida ◽  
H. Tasaki ◽  
M. Konagai ◽  
K. Takahashi
Keyword(s):  
Band Gap ◽  
Optical Band Gap ◽  
Wide Band ◽  
Dark Conductivity ◽  
Hydrogen Gas ◽  
Microcrystalline Silicon ◽  
Wide Band Gap ◽  
Wide Gap ◽  
P Type ◽  
Photochemical Vapor Deposition

AbstractDoped hydrogenated microcrystalline silicon (μc-Si:H) and fluorinated hydrogenated microcrystalline (μc-Si:F:H) films were prepared by the mercury photosensitized decomposition of a disilane-hydrogen or a difluorosilane-hydrogen gas mixture, respectively. The maximum dark conductivity and optical band gap of μc-Si:H films were respectively 20 S•cm−1 and ∼2.0 eV for n-type and 1 S•cm−1 and 2.3 eV for p-type. A higher dark conductivity as much as 50 S•cm−1 and a wide gap of 2.0 eV were obtained for n-type μc-Si:F:H. It is most significant that the gaseous ratio of hydrogen to disilane should be enhanced to obtain such a highly conductive and wide gap film. The crystallinity of the photo-deposited μc-Si:H films appeared to be improved in comparison with that of films by the conventional plasma glow discharge technique.

Application of halide vapor phase epitaxy for the growth of ultra-wide band gap Ga2O3

2019 ◽  
Vol 40 (1) ◽  
pp. 011805 ◽  
Author(s):  
Xiangqian Xiu ◽  
Liying Zhang ◽  
Yuewen Li ◽  
Zening Xiong ◽  
Rong Zhang ◽  
...  
Keyword(s):  
Band Gap ◽  
Vapor Phase ◽  
Wide Band ◽  
Vapor Phase Epitaxy ◽  
Ultra Wide Band ◽  
Wide Band Gap

Optical Transitions on CdS/CdTe CVD Heterostructures

1992 ◽  
Vol 242 ◽  
Author(s):  
Claude Boemare ◽  
M H Nazare
Keyword(s):  
Excited State ◽  
Band Gap ◽  
Wide Band ◽  
Hexagonal Wurtzite Structure ◽  
Hexagonal Structure ◽  
Optical Transitions ◽  
Wide Band Gap ◽  
High Quality ◽  
Photoluminescence Study ◽  
Neutral Acceptor

ABSTRACTWide-band gap II-VI semiconductors have direct bandgaps which cover the energy range from the red to the u-v. This makes such compounds ideal for optoelectronic applications. CdS has a band gap of 2.42 eV and becomes potentially useful for the green region of the spectrum. However, because CdS has a preference to adopt the hexagonal wurtzite structure, epitaxial growth of this semiconductor is complicated. Nevertheless succesful growth of CdS layers onto CdTe is possible. We report a detailed photoluminescence study of CdS/CdTe heterostructures grown by CVD. The CdS layers have high quality hexagonal structure. Luminescence lines are narrow enough and we could detect a splitting ocurring on the excited state of a neutral acceptor bound exciton, at 2.5462 eV.

Development of flexible Mg and Ga co-doped ZnO thin films with wide band gap energy and transparent conductive characteristics

2014 ◽  
Vol 585 ◽  
pp. 608-613 ◽  
Author(s):  
Seung Wook Shin ◽  
In Young Kim ◽  
G.V. Kishor ◽  
Yeong Yung Yoo ◽  
Young Baek Kim ◽  
...  
Keyword(s):  
Thin Films ◽  
Band Gap ◽  
Wide Band ◽  
Band Gap Energy ◽  
Zno Thin Films ◽  
Wide Band Gap ◽  
Gap Energy ◽  
Doped Zno ◽  
Co Doped
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