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First principles study of electronic structures of Cd0.9375Co0.0625X (X?=?S, Se, Te) for magnetic, optical and thermoelectric device applications
摘要： The present article investigates the structural and electronic properties of Co doped (xCo = 6.25%) CdS/Se/Te diluted magnetic semiconductors to understand the optical and thermoelectric characteristics. The electronic properties, computed by applying generalized gradient approximation (GGA) and then modified Becke Johnson (mBJ) functional, are contrasted to identify the appropriate electronic parameters. The stable ferromagnetic states have been justified to arise due to the p-d hybridization that has been found responsible in inducing magnetic moments at the interstitial and at the non-magnetic sites. The computed direct band gap and the exchange constants (N0α and N0β) have suggested, respectively, the potential optical and spintronic device applications. The studied compounds operate within visible-ultraviolet energy range. The thermoelectric response improves with temperature, while deteriorated due to Co doping. The studied compounds exhibiting various significant physical properties evidence the potential consumption in various technologically important spintronic, optoelectronic and thermoelectric devices.
关键词： Optical properties,Ferromagnetism,Diluted magnetic semiconductors,Thermoelectric properties,mBJ potential
更新于2025-09-23 15:23:52
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Ferromagnetism and Carrier Transport in n-type Diluted Magnetic Semiconductors Ge0.96?xBixFe0.04Te Thin Film
摘要： The structural, Hall effect, electronic transport, and magnetic properties of Ge0.96?xBixFe0.04Te epitaxial thin film as prepared by pulsed laser deposition technique were reported. X-ray diffraction patterns including linear scans and phi scans confirmed that all films are high quality epitaxy and crystallinity. With the substitution of high valence Bi for Ge element, we found that the previous carriers of hole were changed to electron, which was testified by the negative slopes obtained from the measurements of Hall effect under different temperatures. The electronic transports show a typical semiconductor behavior and can be understood by the small polaron hopping model because the lattice distortions increase the electron-phonon interaction. An obvious ferromagnetic properties occur in the high Bi-doping Ge0.64Bi0.32Fe0.04Te rather than in that with low Bi-doping concentration, indicating that the ferromagnetic establishment is entirely dependent on carrier’s transmissions. The first-principles calculation performed on this system also reveals that the ferromagnetic state exactly exists in the present n-type diluted magnetic semiconductors with Bi co-dopants.
关键词： N-type semiconductor,Ferromagnetism,Diluted magnetic semiconductors
更新于2025-09-23 15:22:29
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Half-metallic ferromagnetic behavior in (Ga, Cr)N and (Ga, Cr, V)N compounds for spintronic technologies: Ab-initio and Monte Carlo methods
摘要： In this article, we investigate the magnetic- and electronic-proprieties of GaN doped with simple- and double-impurities utilizing Ab-initio and Monte Carlo studies. We have predicted that (Ga, Cr)N and (Ga, Cr, V)N compounds exhibit ferromagnetic- and halfmetallic-behavior with 100% spin-polarization at the Fermi-level. Moreover, we have found that Ga1-xCrxN and Ga1-2xCrxVxN (x = 0.04, 0.05 and 0.06) show a 2nd order ferromagnetic transition and that their Tc is above room temperature. These predictions make (Ga, Cr)N and (Ga, Cr, V)N compounds strong-candidates for spintronic-technologies.
关键词： Ab-initio calculations,Monte Carlo method,Diluted magnetic semiconductors,Spintronic,Gallium Nitride
更新于2025-09-23 15:22:29
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Influences of Mn doping on the microstructural, semiconducting and optoelectronic properties of HgO nanostructure films
摘要： Mn-doped HgO nanostructured thin films (Hg1-xMnxO) have been prepared using electron beam evaporation technique on Corning glass (1022) substrate at room temperature with different concentrations x = 0, 0.015, 0.05, 0.1, 0.15 and 0.2. The microstructural, morphological, semiconducting and optoelectronic properties of the films have been investigated. The X-ray diffraction spectra suggest a hexagonal wurtzite type structure with lattice parameters decreased with increasing Mn content. It was found that the average particle size of the films decreases with increasing Mn doping which is confirmed by FE-SEM and AFM micrographs. The optical band gap of the investigated Mn-doped HgO nanocrystalline films is determined from the absorption coefficient and found to increase with the increase of Mn concentration which is attributed to the sp-d exchange interaction and/or the quantum confinement effect. The refractive index and extinction coefficient of the Mn-doped HgO films are also reported. The refractive index dispersion n(λ) is analyzed by single-effective-oscillator dispersion model proposed by the Wemple–DiDomenico (WDD). The oscillator parameters were estimated. The obtained dispersion values are suitable for the design of optoelectronic devices.
关键词： microstructure properties,Nanomaterial,Diluted magnetic semiconductors,single oscillator parameters,optical properties
更新于2025-09-19 17:15:36
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Ge <sub/>x</sub> Si <sub/>1-x</sub> Virtual-Layer Enhanced Ferromagnetism in Self-assembled Mn <sub/>0.06</sub> Ge <sub/>0.94</sub> Quantum Dots Grown on Si Wafers by Molecular Beam Epitaxy
摘要： The self-assembled Mn0.06Ge0.94 quantum dots (QDs) on Si substrate or GexSi1-x virtual substrate (VS) were grown by molecular beam epitaxy. The GexSi1-x VS of different thicknesses and Ge compositions x were utilized to modulate the ferromagnetic properties of the above QDs. The MnGe QDs on GexSi1-x VS show a significant enhanced-ferromagnetism with a Curie temperature above 220 K. On the basis of the microstructural and magnetization results, the ferromagnetic properties of the QDs on GexSi1-x VS are believed to come from the intrinsic MnGe ferromagnetic phase rather than any intermetallic ferromagnetic compounds of Mn and Ge. At the same time, we found that by increasing Ge composition x of GexSi1-x VS, the ferromagnetism of QDs grown on VS will markedly increase due to the improvements of hole concentration and Ge composition inside the QDs. These results are fundamentally important in the understanding and especially to the realization of high Curie temperature MnGe diluted magnetic semiconductors.
关键词： ferromagnetism,molecular beam epitaxy,diluted magnetic semiconductors,GexSi1-x virtual substrate,MnGe quantum dots
更新于2025-09-19 17:13:59
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Photocatalytic response of Fe, Co, Ni doped ZnO based diluted magnetic semiconductors for spintronics applications
摘要： Novel attempts were made to prepare diluted magnetic semiconductors separately with 10 at.% each of Fe, Co and Ni doped ZnO by sol-gel method. The XRD analysis of the films detect wurtzite ZnO as the pure phase present in the synthesized films. The average particle size of 10 at.% Fe, Co, Ni doped and pristine ZnO derived films are found as 10.01 nm, 12.03 nm, 15.36 nm and 16.16 nm respectively. The absorbance spectra of the oxides reveal intrinsic band gap of ZnO, Fe2O3, CoO and NiO are 3.29 eV, 2.53 eV, 2.42 eV and 3.64 eV respectively. The near band edge absorbance of pure ZnO was recorded as about 377 nm (～3.29 eV) which shifts to lower wavelength with reduction in particle size in Ni, Co and Fe doped ZnO sample as the effect of quantum confinement. The PL spectra of the developed films reveal multiple peaks between 450 nm and 500 nm, on excitation wavelength at 370 nm, as the evidence of photochemical properties of the samples. Vibrating sample magnetometer analysis reveals 10 at.% Fe doped ZnO posses minimum value of squareness 0.118 and coersivity 177.738 Oe which prove it to be the best magnetic material among all four samples prepared. Raman spectra show evidence of phonon confinement for 10 at.% Fe doped ZnO sample by broadening of Eg, T2g and A1g peaks, which is not so prominent for other samples. In addition, the photochemical degradation reaction is maximum for 10 at.% Fe doped ZnO sample which proves to be most suitable material for optoelectronic devices.
关键词： Solar spin,Zinc oxide,Photocatalytic response,Diluted magnetic semiconductors,Phonon confinement
更新于2025-09-10 09:29:36
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Reference Module in Materials Science and Materials Engineering || Nano-Structured Diluted Magnetic Semiconductors
摘要： Diluted magnetic semiconductors (DMS) materials have attracted much interest in recent years because of the combination of both semiconducting and magnetic properties within the same material. Among the potential applications that DMS materials can offer is spintronics which exploits both the electron charge associated with the intrinsic spin of the electron. DMS are semiconductors doped with magnetic impurities. Physical properties, like band gap energy or magnetism, are now not only a function of the particle size but also of the doping level. Therefore, ordered arrays of nanometer sized magnetic semiconductors are promising components for new devices in magneto- or spin electronics.
关键词： Diluted magnetic semiconductors,Band gap energy,Spintronics,Nanometer sized magnetic semiconductors,Magnetic impurities
更新于2025-09-09 09:28:46
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Structural, Optical, and Magnetic Properties of Hydrothermally Grown Fe-Doped ZnO Nanorod Arrays on Glass Substrate
摘要： In this paper, undoped and Fe-doped ZnO nanorod arrays were grown on glass substrate by a facile hydrothermal method. Structural, optical, and magnetic properties of the prepared nanorods were investigated. Structural investigation clearly showed that the prepared nanorods had single phase wurtzite structure without any secondary phases and the prepared undoped and Fe-doped nanorods were grown vertically. The optical characterization revealed that the optical band gap of ZnO nanorods was decreased by increasing the value of Fe concentration. Furthermore, the formation of diluted magnetic semiconductor nanorod arrays was verified. The origin of room temperature ferromagnetism is explained by the bound magnetic polaron concept.
关键词： Diluted magnetic semiconductors,Bound magnetic polaron,Nanorod arrays,Fe-doped ZnO
更新于2025-09-09 09:28:46