Masoudeh Maleki
@fshiau.ac.ir
Assistant professor in Physics, Department of Science
Fouman and Shaft Branch, Islamic Azad University
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Scopus Publications
M. Maleki
Institute of Physics, Polish Academy of Sciences
M. Maleki
Springer Science and Business Media LLC
Nanostructured nitrogen-, niobium-, and tantalum-doped tin oxides are investigated by first-principle calculations. First, the band structure, bond length, density of states, and projected density of states of pure tin oxide are evaluated. Then, the effect of nitrogen, niobium, and tantalum doping substituting O and Sn is compared with the pure case. In all cases, substitutional doping with N results in p-type conductivity whereas n-type conductivity results from Nb and Ta doping. Substitution of O with N and of Sn with Nb or Ta increases the bandgap of the structure, while substitution of Sn and Nb with N reduces the bandgap.
M. Maleki and S.M. Rozati
Institute of Physics, Polish Academy of Sciences
In this paper, the e ect of substrate temperature on the electrical, structural, morphological and optical properties of nanostructured polycrystalline zinc oxide thin lms were investigated by the Hall measurement, Xray di raction, scanning electron microscopy and UV-visible spectrophotometer, respectively. Then these modi ed thin lms were deposited on two kinds of single crystal and polycrystalline of nand p-type Si in three di erent substrate temperatures of 300, 400 and 500 ◦C by low cost atmospheric pressure chemical vapor deposition method. Like the samples grown on the glass substrate, with increase of the temperature in samples grown on single crystal Si, preferred orientation changes from (100) to (002), while in samples deposited on poly crystalline Si, preferred orientation remains (100).
Masoudeh Maleki and Seyed Mohammad Rozati
Wiley
Pure tin oxide (TO) films are deposited onto glass substrates at various substrate angles relative to the source position by a simple and inexpensive method of atmospheric pressure (AP)CVD. The deposition temperature is constant at about 500°C, and oxygen with a flow rate of 100 sccm is used as both the carrier gas and the oxidizing agent. Investigation of the sheet resistance shows that resistivity varies between 106 and. 241 Ω/□. X-ray diffraction (XRD) also reveals that the structure is polycrystalline with the preferred orientation of (110) for all films deposited at the various substrate angles. Scanning electron microscopy (SEM) images also reveal a uniform and impacted structure on the surface of all the films. Optical properties show clear changes as a result of the substrate position versus the source.
M MALEKI and S M ROZATI
Springer Science and Business Media LLC
A modified new method of CVD for formation of pure layers of tin oxide films was developed. This method is very simple and inexpensive and produces films with good electrical properties. The effect of substrate temperature on the sheet resistance, resistivity, mobility, carrier concentration and transparency of the films has been studied. The best sheet resistance obtained at substrate temperature of 500 °C was about 27 Ω/cm2. X-ray diffraction showed that the structure of deposited films was polycrystalline with a grain size between 150–300 Å. The preferred orientation was (211) for films deposited at substrate temperature of about 500 °C. FESEM micrographs revealed that substrate temperature is an important factor for increasing grain size and modifies electrical parameters. UV-visible measurement showed reduction of transparency and bandgap of the layers with increasing substrate temperature.
M Maleki and S M Rozati
IOP Publishing
Pure tin oxide films were deposited onto glass substrate at different oxygen flow rates by a simple and inexpensive method of air pressure chemical vapor deposition. The deposition temperature was kept constant at about 500 °C, and oxygen with a flow rate of 0–400 sccm was used as both a carrier gas and the oxidizing agent. Investigation of the electrical parameters variations showed that these parameters vary with oxygen flow rate, reaching an optimum value at the flow rate of 100 sccm. X-ray diffraction (XRD) also revealed the structure to be polycrystalline for all films deposited at different oxygen flow rates. In agreement with the XRD results, field emission scanning electron microscopy micrographs showed a reduction in grain size corresponding to increasing flow rates until 200 sccm, and after that, with a further increase of flow rate, the grain size increased.
H. Panahi and M. Maleki
Wiley
The effects of hydrostatic pressure on the donor binding energy in GaAs–Ga0.7Al0.3As quantum wells have been studied in the effective mass approximation, using a variational approach for hydrogenic ground state 1s and excited states 2s, 2px, 3px. Results obtained show that the donor binding energy variation with the well width and the position of impurity under pressure is similar to that without pressure. The intra donor squared transition matrix elements are calculated as functions of impurity position in the presence of hydrostatic pressure. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
H. Panahi and M. Maleki
Science Alert