Manzar Abbas | COMSATS Institute of Information Technology (original) (raw)

Manzar Abbas

i am a researcher in the field of solar cells, sensors and semiconductor materials.
Phone: 923335206046
Address: House #20, Street #1, Shaheen Town Islamabad, Pakistan

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Papers by Manzar Abbas

MRS Proceedings, 1992

ABSTRACT Both B- and P- doped silicon films deposited by Low Pressure Chemical Vapor Deposition (... more ABSTRACT Both B- and P- doped silicon films deposited by Low Pressure Chemical Vapor Deposition (LPCVD) at 300 °C (p-type) and 420 °C (n-type) have been characterized by optical absorption, Photothermal Deflection Spectroscopy (PDS), resistivity, Elastic Recoil Detection Analysis (ERDA), Transmission Electron Microscopy (TEM), Convergent-Beam Electron Diffraction (CBED) and Raman spectroscopy measurements. P-doped films, deposited at large PH3 flux rates, show a high degree of microcrystallinity, indicating that P activates the nucleation process even at low temperatures. In this case, values of activation energy of resistivity as low as 0.007 eV were obtained. Both TEM and RAMAN results confirm a volume percentage of micro crystallinity above 30%. On the contrary, B-doped samples are not microcrystalline at least in the doping range investigated, and show a behaviour not different from samples deposited by PECVD.

A low cost and relatively fast growing material processing technique is used to prepare Nano/meso... more A low cost and relatively fast growing material processing technique is used to prepare Nano/meso-porous thin films of Titanium Dioxide (TiO 2 ) from the colloidal solution of nano particles of TiO 2. Both characteristic peaks of anatase and rutile are confirmed by XRD spectra and SEM results confirm the films to be nano/meso-porous. Fairly large densities of cracks were observed in the films. It is shown that a purely nano-porous uniform film without cracks may be prepared with lower substrate temperature during spray and low temperature baking for over night.

Sensors and Actuators A Physical

$Research paper thumbnail of Optical properties of higher and lower refractive index composites in solar selective coatings$

Solar Energy Materials and Solar Cells, 2002

The focus of attention in this study was the choice of material for optically solar selective coa... more The focus of attention in this study was the choice of material for optically solar selective coatings on the basis of their optical constants. A computer programme which calculates the optical constants, solar absorptance at air mass (AM)-2, a, and thermal emittance at 300 K, e, of the 200-nm-thick selective coating on the assumption of both the Maxwell Garnett and Bruggeman theories for the metallic volume fraction below and above 0.3 respectively, was used to design the structure of the composite films. Two systems of composite thin films of metal and dielectric were investigated experimentally, fabricated by RF and DC sputter coater and were verified with computer simulations. One system consist of lower refractive index composites such as Ni:SiO 2 and the other of higher refractive index composites such as V:Al 2 O 3 in the spectral range of 0.3-20 mm. These films were fabricated on infrared reflective substrates such as nickel plated copper or aluminium. Results of the copper substrates are being presented here. For comparison and verification, tungsten, cobalt and chromium based composites, having different refractive indices, were also investigated which validated the concept of the choice of material in selective coatings. It was observed that high refractive index composites have lower reflective properties by choosing suitable metallic volume fraction in dielectric and antireflection coating. The higher value of the imaginary part of refractive index, k, is responsible for higher absorption by a factor a l ¼ 4pk=l. Solar absorptance of 0.98 and 0.96 was achieved by simulation and experimental findings with less than 0.05 thermal emittance for 200 nm thick composites of V:Al 2 O 3 . It results that higher values of both n and k of the material are more suitable in solar selective coatings. r (M. Farooq). 0927-0248/02/$ -see front matter r 2002 Elsevier Science B.V. All rights reserved. PII: S 0 9 2 7 -0 2 4 8 ( 0 1 ) 0 0 0 4 5 -9

Journal of Materials Sciences …, 2009

英文摘要Cadmium telluride (cdte) thin films were grown on well-cleaned glass substrates by thermal va... more 英文摘要Cadmium telluride (cdte) thin films were grown on well-cleaned glass substrates by thermal vacuum evaporation technique. set of samples were heated in atmosphere at 450℃, next set of samples were annealed under vacuum at 300℃ and other set of samples were ...

bzu.edu.pk

▼ Journal of Research (Science), Bahauddin Zakariya University, Multan, Pakistan. Vol. 17, No. 2,... more ▼ Journal of Research (Science), Bahauddin Zakariya University, Multan, Pakistan. Vol. 17, No. 2, April 2006, pp. 137-144 ... OPTICAL BAND GAP OF ZnO THIN FILMS ... MY Nadeem, S. Liaqat Ali, MF Wasiq, AM Rana Department of Physics, Bahauddin Zakariya University, ...