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Azam Mayabadi

Bio: Azam Mayabadi is an academic researcher from Savitribai Phule Pune University. The author has contributed to research in topics: Thin film & Raman spectroscopy. The author has an hindex of 8, co-authored 21 publications receiving 193 citations. Previous affiliations of Azam Mayabadi include Amirkabir University of Technology.

Papers
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Journal ArticleDOI
TL;DR: In this paper, the influence of deposition time on structural, morphological and optical properties of nanocrystalline thin films of TiO2 on glass substrates was systematically investigated.

59 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reported synthesis of nanocrystalline Kesterite copper zinc tin sulfide (CZTS) films by RF magnetron sputtering method, which can improve the conversion efficiency by reducing recombination rate of photo-generated charge carriers due to larger grain size.
Abstract: In present work, we report synthesis of nanocrystalline Kesterite copper zinc tin sulfide (CZTS) films by RF magnetron sputtering method. Influence of calcination temperature on structural, morphology, optical, and electrical properties has been investigated. Formation of CZTS has been confirmed by XPS, whereas formation of Kesterite-CZTS films has been confirmed by XRD, TEM, and Raman spectroscopy. It has been observed that crystallinity and average grain size increase with increase in calcination temperature and CZTS crystallites have preferred orientation in (112) direction. NC-AFM analysis revealed the formation of uniform, densely packed, and highly interconnected network of grains of CZTS over the large area. Furthermore, surface roughness of CZTS films increases with increase in calcination temperature. Optical bandgap estimated using UV–Visible spectroscopy decreases from 1.91 eV for as-deposited CZTS film to 1.59 eV for the film calcinated at 400 °C which is quite close to optimum value of bandgap for energy conversion in visible region. The photo response shows a significant improvement with increase in calcinations temperature. The employment these films in solar cells can improve the conversion efficiency by reducing recombination rate of photo-generated charge carriers due to larger grain size. However, further detail study is needed before its realization in the solar cells.

39 citations

Journal ArticleDOI
TL;DR: In this paper, the authors reported synthesis of orthorhombic-molybdenum trioxide (α-MoO3) thin films using home-build hot wire CVD (HW-CVD) method simply by heating the Mo filament in a controlled O2 atmosphere.
Abstract: In present work, we report synthesis of orthorhombic-molybdenum trioxide (α-MoO3) thin films using home-build hot wire-CVD (HW-CVD) method simply by heating the Mo filament in a controlled O2 atmosphere. The formation of α-MoO3 was confirmed by low angle-XRD and Raman spectroscopy. Low angle-XRD analysis revealed that α-MoO3 crystallites have orientations along (110), (101) and (111) directions while Raman spectroscopy analysis shows two prominent vibrational modes ~819 and ~994 cm−1 associated with Mo2–O and Mo=O respectively. SEM and TEM analysis show the formation of nano-sheets like morphology of α-MoO3 thin films. The SAED pattern shows highly crystalline nature of α-MoO3. The humidity-sensing properties were investigated at room temperature by fabricating the two probe device. The humidity sensing results showed n-type behavior of α-MoO3. The maximum humidity sensitivity of ~6957% along with response time of ~66 s and recovery time of ~5 s were observed for α-MoO3 thin film humidity sensor device. Our results have opened up a new avenue to grow α-MoO3 for humidity sensor applications.

39 citations

Journal ArticleDOI
04 Feb 2014
TL;DR: In this paper, structural, optical, and electrical properties of hydrogenated silicon carbide (SiC:H) films, deposited from silane (SiH4) and methane (CH4) gas mixture by HW-CVD method, were investigated.
Abstract: Structural, optical, and electrical properties of hydrogenated silicon carbide (SiC:H) films, deposited from silane (SiH4) and methane (CH4) gas mixture by HW-CVD method, were investigated. Film properties are carefully and systematically studied as function of deposition pressure which is varied between 200 mTorr and 500 mTorr. The deposition rate is found to be reasonably high (9.4 nm/s 15.54 nm/s). Formation of SiC:H films is confirmed by FTIR, Raman, and XPS analysis. XRD and Raman analysis revealed that with increasing deposition pressure amorphization occurs in SiC:H films. FTIR spectroscopy analysis shows that bond density of C–H decreases while Si–C and Si–H bond densities increase with increasing deposition pressure. Total hydrogen content increases with increasing deposition pressure and was found to be <20 at.%. The absence of band ~1300–1600 cm−1 in the Raman spectra implies negligible C–C bond concentration and formation of nearly stoichiometric SiC:H films. The band gap shows increasing trend with increasing deposition pressure. The high value of Urbach energy suggests increased structural disorder in SiC:H films. Finally, it has been concluded that CH4 can be used as effective carbon source in HW-CVD method to prepare stoichiometric SiC:H films.

25 citations

Journal ArticleDOI
TL;DR: In this article, the influence of boron doping on structural, optical, morphological and electrical properties of 3C-SiC films have been investigated by using HW-CVD using silane (SiH4)/methane (CH4)/diborane (B2H6) gas mixture.

18 citations


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01 Jan 2016

1,664 citations

Journal Article
TL;DR: In this paper, a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons was proposed to increase the red shift and broadening of the signal from microcrystalline silicon films.
Abstract: The red shift and the broadening of the Raman signal from microcrystalline silicon films is described in terms of a relaxation in the q-vector selection rule for the excitation of the Raman active optical phonons. The relationship between width and shift calculated from the known dispersion relation in c-Si is in good agreement with available data. An increase in the decay rate of the optical phonons predicted on the basis of the same model is confirmed experimentally.

105 citations

Journal ArticleDOI
01 Aug 2019-Small
TL;DR: Benefiting from the sensitive and rapid response to fingertip humidity, the sensors are successfully applied to both a smart noncontact multistage switch and a novel flexible transparent noncontact screen for smart mobile devices, demonstrating the potential of the MoO3 nanosheets-based humidity sensors in future HMI systems.
Abstract: The development of noncontact humidity sensors with high sensitivity, rapid response, and a facile fabrication process is urgently desired for advanced noncontact human-machine interaction (HMI) applications. Here, a flexible and transparent humidity sensor based on MoO3 nanosheets is developed with a low-cost and easily manufactured process. The designed humidity sensor exhibits ultrahigh sensitivity, fast response, great stability, and high selectivity, exceeding the state-of-the-art humidity sensors. Furthermore, a wearable moisture analysis system is assembled for real-time monitoring of ambient humidity and human breathing states. Benefiting from the sensitive and rapid response to fingertip humidity, the sensors are successfully applied to both a smart noncontact multistage switch and a novel flexible transparent noncontact screen for smart mobile devices, demonstrating the potential of the MoO3 nanosheets-based humidity sensors in future HMI systems.

94 citations

Journal ArticleDOI
TL;DR: In this article, a high-performance infrared photodetectors based on a MoS2/CdTe p-n heterojunction with type-II band alignment was constructed and investigated.
Abstract: High-performance infrared photodetectors (PDs) have attracted much attention due to their great significance in military and industrial applications. The improvement of two-dimensional (2D) materials offers an open platform for designing various high-performance PDs, especially in the infrared region, which can overcome the drawbacks of the traditional epitaxial thin film based PDs, such as the complicated preparation processes, low-temperature operating conditions and inability to be miniaturized. In this work, a high-performance infrared PD based on a MoS2/CdTe p–n heterojunction with type-II band alignment was constructed and investigated. This PD showed a broadband photoresponse from 200 nm to 1700 nm, which is far beyond the band-gaps of MoS2 and CdTe. Moreover, a high responsivity, specific detectivity and fast response speed were achieved. These results demonstrate that the MoS2/CdTe p–n heterojunction has great potential in room-temperature infrared detection, and provide a way to design high-performance infrared PDs for other 2D materials.

75 citations

Journal ArticleDOI
TL;DR: An ultraviolet photodiode based on rutile TiO2 nanorods, which were grown on p-type Si substrate seeded with a TiO 2 layer, was synthesized by radiofrequency reactive magnetron sputtering as mentioned in this paper.
Abstract: An ultraviolet photodiode based on rutile TiO2 nanorods, which were grown on p-type Si substrate seeded with a TiO2 layer, was synthesized by radiofrequency reactive magnetron sputtering. Chemical bath deposition was performed to grow rutile TiO2 nanorods. X-ray diffraction and field emission-scanning electron microscopy were conducted to determine the structural and optical properties of the sample. The synthesized TiO2 nanorods exhibited tetragonal rutile structure. The device showed 3.79 × 102 sensitivity when it was exposed to 325 nm light (1.6 mW/cm) at 5 V bias voltage. In addition, the internal gain of the photosensor was 4.792 and the photoresponse peak was 460 mA/W. The photocurrent was 6.09 × 10−4 A. The response and recovery times of the PD were 50.8 and 57.8 ms, respectively, upon illumination of a pulsed UV light (325 nm, 1.6 mW/cm2) at 5 V bias voltage.

73 citations