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.

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.

Band modification of graphene by using slow Cs+ ions

RSC Advances ◽  
2016 ◽  
Vol 6 (11) ◽  
pp. 9106-9111 ◽  
Author(s):  
Sijin Sung ◽  
Sang-Hoon Lee ◽  
Paengro Lee ◽  
Jingul Kim ◽  
Heemin Park ◽  
...  
Keyword(s):  
Band Gap ◽  
Wide Band ◽  
Fine Tuning ◽  
Dirac Fermions ◽  
Wide Band Gap ◽  
Band Gap Engineering ◽  
Cs Ions

We report new wide band gap engineering for graphene using slow Cs+ ions, which allows both fine-tuning and on–off switching capability of the band gap in a range suitable for most applications sustaining the nature of Dirac fermions.

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 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 3C-SiС Hetero-Epitaxially Grown on Silicon Compliance Substrates and New 3C-SiС Substrates for Sustainable Wide-Band-Gap Power Devices (CHALLENGE)

2018 ◽  
Vol 924 ◽  
pp. 913-918 ◽  
Author(s):  
Francesco La Via ◽  
Fabrizio Roccaforte ◽  
Antonino La Magna ◽  
Roberta Nipoti ◽  
Fulvio Mancarella ◽  
...  
Keyword(s):  
Band Gap ◽  
Defect Density ◽  
Narrow Band ◽  
Wide Band ◽  
Growth Conditions ◽  
Power Devices ◽  
Wide Band Gap ◽  
New Material ◽  
Numerical Tools

The cubic polytype of SiC (3C-SiC) is the only one that can be grown on silicon substrate with the thickness required for targeted applications. Possibility to grow such layers has remained for a long period a real advantage in terms of scalability. Even the relatively narrow band-gap of 3C-SiC (2.3eV), which is often regarded as detrimental in comparison with other polytypes, can in fact be an advantage. However, the crystalline quality of 3C-SiC on silicon has to be improved in order to benefit from the intrinsic 3C-SiC properties. In this project new approaches for the reduction of defects will be used and new compliance substrates that can help to reduce the stress and the defect density at the same time will be explored. Numerical simulations will be applied to optimize growth conditions and reduce stress in the material. The structure of the final devices will be simulated using the appropriated numerical tools where new numerical model will be introduced to take into account the properties of the new material. Thanks to these simulations tools and the new material with low defect density, several devices that can work at high power and with low power consumption will be realized within the project.

Solar-Blind Ultraviolet Photodetectors Based on Vertical Graphene-Hexagonal Boron Nitride Heterostructures

MRS Advances ◽  
2020 ◽  
Vol 5 (37-38) ◽  
pp. 1993-2002
Author(s):  
Jesse E. Thompson ◽  
Darian Smalley ◽  
Masahiro Ishigami
Keyword(s):  
Boron Nitride ◽  
Band Gap ◽  
Hexagonal Boron Nitride ◽  
Wide Band ◽  
Infrared Light ◽  
Visible Range ◽  
Wide Band Gap ◽  
Solar Blind ◽  
Key Factor ◽  
Ultraviolet Photodetectors

AbstractPhotodetectors operating in the ultraviolet (UV) play a pivotal role in applications such as ozone monitoring and biosensing. One key factor to successfully implementing such photodetectors is that they must be solar-blind to avoid detecting ambient visible and infrared light. Unfortunately, UV photodetectors based on silicon and other typical semiconductors are not natively solar-blind, since their band gap energies are in the visible range. Hexagonal boron nitride (h-BN) is an example of a wide band gap semiconductor which shows promise for use as the absorbing medium in a UV photodetector device, since its band gap is wide enough to make it inherently insensitive to light in the visible range and above. Here we report on the fabrication and characterization of a graphene-h-BN-heterostructure photodetector which utilizes a vertical geometry, in principle allowing for highly scalable production. We find that our device shows a finite photoresponse to illumination by a 254 nm light source, but not to a 365 nm source, thus suggesting that our device is solar-blind.

scholarly journals Optical applications of wide-band-gap gallium oxide

2014 ◽  
Vol 70 (a1) ◽  
pp. C1411-C1411
Author(s):  
Takayoshi Oshima
Keyword(s):  
Single Crystal ◽  
Band Gap ◽  
Single Crystals ◽  
Water Splitting ◽  
Wide Band ◽  
Crystal Plate ◽  
Wide Band Gap ◽  
Solar Blind ◽  
Single Crystal Plate ◽  
Optical Applications

Ga2O3 have been attracting much attention as a wide-band-gap semiconductor owing to a large band-gap of 4.8 eV and the availability of high-quality and large-sized single crystals, which are advantageous over conventional wide-band-gap semiconductors. This presentation focuses on optical applications using Ga2O3 single crystals: photodetectors and photoelectrodes, both of which show interesting and promising properties[1,2]. As for photodetectors, a PEDOT-PSS Schottky and In ohmic contacts were prepared on front and back surfaces of a n-type Ga2O3 single crystal plate, respectively, to fabricate a photovoltaic detector. The detector operated at zero bias (V = 0 V) exhibited high responsivities in the solar-blind region (< 280 nm). Incident photon to current conversion efficiency (IPCE) was as high as 21% at 240 nm and a 240-to-300 nm rejection ratio was as large as 10^4, indicating that the detector can be applicable for flame sensing. In fact, the detector successfully detected a flame by distinguishing several nW/cm2 weak solar-blind light from a flame under a strong fluorescent lamp illumination without using visible-cut filters. As for photoelectrodes, an n-type Ga2O3 single crystal plate with In ohmic contact on the back side was used for characterization. From impedance analysis, the conduction and valence band-edges in aqueous solutions were found to be 1.1 V higher and 2.5 V lower than the H+/H2 and O2/H2O redox potentials, respectively. These potential differences, or overpotentials for water splitting, are large enough for photolysis of water. When the photoelectrode was excited by photons, H2 and O2 gases evolved from a counter Pt electrode and the photoelectrode, respectively. The highest IPCE of 36% was obtained at 240 nm. Stoichiometric water splitting was demonstrated at V = 1V without using co-catalysts. These results encourage the notion of Ga2O3 optical applications and also contribute for developing Ga2O3 semiconductor studies.

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