Tasnim Kamal | University of Delaware (original) (raw)

Papers by Tasnim Kamal

International Journal for Research in Applied Science and Engineering Technology (IJRASET), 2018

In this work, CdS, ZnS and ZnO thin films have been deposited by chemical bath deposition techniq... more In this work, CdS, ZnS and ZnO thin films have been deposited by chemical bath deposition technique and dried at 150 0 C for 30 min. Detail optical and structural characterizations have been done by UV-Vis spectroscopy and X-ray Diffraction analysis to get a comparative study between 3 samples. The XRD analysis has revealed that CdS and ZnO have hexagonal wurtzite crystal structures while ZnS has Zinc blend crystal structure. Lattice parameter and crystallite size were also measured from XRD. From UV spectra it is seen that ZnS and ZnO have transmittance in the range of (85-90) % which was greater than that of CdS. Deposited CdS, ZnS and ZnO reportedly have band gaps of 2.0 eV, 3.63 eV and 3.65 eV respectively. It is proposed that among 3 samples ZnO has more suitable properties as the window layer for thin film solar cell.

" Access to Information for all " that ensure the balanced development from root to vertex of a c... more " Access to Information for all " that ensure the balanced development from root to vertex of a country. As village is considered as the root of every country in South Asia, it is needed to ensure the sustainable development for every village.Concept of Smart Village is arisen for this purpose where each villager is kept under the service of ICT that minimize the digital distance between urban and rural and escort the digital service along with technical help and vocational training in front of the villager's door and make their lifestyle easier and drive their economic progress. But the poor illiterate villagers do not have the luxury of accessing modern technology due to poverty and also can not gain knowledge from the internet due to their lack of education. So, there must be a group of scholars along with some dedicated volunteers and professionals working under an institution in every village to make it a smart village and contribute to the development of the country. Information, Innovation & Implementation Center (IIIC) is such an institution which will dedicatedly work on different sectors in transforming a village into a smart and sustainable one.

Cadmium sulfide (CdS) is the n-type buffer layer with band gap of 2.42 eV. Cadmium sulfide (CdS) ... more Cadmium sulfide (CdS) is the n-type buffer layer with band gap of 2.42 eV. Cadmium sulfide (CdS) buffer layer of CZTS solar cell was deposited on soda-lime glass substrates by the Chemical Bath Deposition(CBD) method, using anhydrous Cadmium chloride(CdCl 2) and Thiourea (CS(NH 2) 2). Deposition of CdS using CBD is based on the slow release of Cd 2+ ions and S 2-ions in an alkaline bath which is achieved by adding complexing agent ammonia (NH 3). The influence of bath deposition time on the structural, morphological, and optical properties of these films are investigated. The deposited films are studied by means of XRD, SEM, and UV-Vis spectrometry. The films deposited under optimum conditions (deposition time, t d =70 min [S]/[Cd] =3.5) shows good structural and optical properties.

CZTS is a new type of an absorber and abundant materials for thin film solar cells (TFSC).Cadmium... more CZTS is a new type of an absorber and abundant materials for thin film solar cells (TFSC).Cadmium sulfide (CdS) is the n-type buffer layer of it with band gap of 2.42 eV. Cadmium sulfide (CdS) buffer layer of CZTS solar cell was deposited on soda-lime glass substrates by the Chemical Bath Deposition(CBD) method, using anhydrous Cadmium chloride(CdCl2) and Thiourea (CS(NH2)2). Deposition of CdS using CBD is based on the slow release of Cd2+ ions and S2- ions in an alkaline bath which is achieved by adding complexing agent ammonia (NH3). The influence of bath temperature and deposition time on the structural, morphological, and optical properties of these films were investigated. The deposited films were studied by means of XRD, SEM, and UV-Vis spectrometry. The films deposited under optimum conditions (Bath temperature, Tb =800C, Deposition time, td =70 min [S]/[Cd] =3.5) were well crystallized .

Thesis Chapters by Tasnim Kamal

CZTS is a new type of an absorber and abundant materials for thin film solar cells (TFSC). Cadmiu... more CZTS is a new type of an absorber and abundant materials for thin film solar cells (TFSC).
Cadmium sulfide (CdS) is the n-type buffer layer of it and its band gap is 2.42 eV. Cadmium
sulfide (CdS) buffer layer of CZTS solar cell was deposited on soda-lime glass substrates by
the Chemical Bath Deposition(CBD) method, using anhydrous Cadmium chloride(CdCl2) and
Thiourea (CS(NH2)2) as sources of cadmium and sulfur ions respectively. Deposition of CdS
using CBD is based on the slow release of Cd2+ ions and S2- ions in an aqueous alkaline bath
and it is achieved by adding a complexing agent that was ammonia (NH3) in this experiment.
To find the optimum thickness various bath temperature and concentration of thiourea were
varied. The influence of bath temperature and deposition time and [S]/[Cd] ratio in the solution
on the structural, morphological, chemical composition and optical properties of these films
were investigated. The deposited films were studied by means of XRD, SEM, EDX, Hall Effect
and UV-Vis spectrometry. XRD results showed that CdS were formed with preferential
orientations of (004) > (111) > (202) for all the investigated films. The films deposited under
optimum conditions (Bath temperature, Tb =800C, Deposition time, td =70 min [S]/[Cd] =3.5)
were relatively well crystallized.

Conference Presentations by Tasnim Kamal

$Research paper thumbnail of Crystal Size and Strain Estimation of 10% Cu doped ZnO Nanoparticles using X-ray Diffraction Data$

2018 4th International Conference on Electrical Engineering and Information & Communication Technology (iCEEiCT), 2018

10% Cu doped ZnO nanoparticles were synthesized by chemical precipitation method using zinc aceta... more 10% Cu doped ZnO nanoparticles were synthesized by chemical precipitation method using zinc acetate dihydrate [Zn(CH 3 COO) 2 .2H 2 O] and cupric nitrate [Cu(NO 3 ) 2 ] as precursors. Debye-Scherrer, Williamson-Hall, Approximation method and Size-strain plot method were used to estimate particle Size and strain from the X-ray line broadening data. Uniform deformation model (UDM), uniform stress deformation model (USDM), uniform deformation energy density model (UDEDM) and size-strain plot method (SSP) were used to calculate stress and energy using XRD peaks. XRD results indicate that prepared Cu doped ZnO have hexagonal wurtzite structure which is in conformity with the SEM image. Particle size was reported from 16-53 nm. One major uniqueness of this work is the use of Approximation method for estimating crystal size and strain and the use of Cohen's method to calculate lattice constant for ZnO which was not reported in any paper earlier.

International Conference on Material Science and Semiconductor Devices (ICMSSD) 2018, 2018

Objective: The aim of this paper is to explore the synthesis of ZnO and Cu doped ZnO nanoparticle... more Objective: The aim of this paper is to explore the synthesis of ZnO and Cu doped ZnO nanoparticles ensuring their reproducibility using locally available chemicals and to analyze detailed structural, morphological and optical characterization of the prepared samples to ensure high quality of the synthesized nanoparticles to develop a high performance optoelectronic device. Experimental Procedure: Cu doped ZnO nanoparticles were prepared using zinc acetate dehydrate and cupric nitrate as the precursors. Then ammonia solution was added dropwise into solution to maintain the pH value The solution container was placed in a water bath and kept at 60 o C for 75 min. 0%, 3%, 5% and 10% Cu doped nanoparticles were precipitated after 72, 48, 96 and 168 hour of aging respectively. After being separated from the solution, samples were annealed at 400 o C for 1h to remove the other inorganic components. Later, the nanopowder samples were characterized using FTIR, XRD, SEM, EDS and UV-VIS NIR Results: From Fourier-transform infrared spectroscopy analysis (FTIR), it is seen that due to Cu atom being slightly lighter than Zn atom, Zn-O stretching bond resulted in an upward shift of the fundamental transverse optical phonon mode [2]. The observed results are consistent with the results given by Singhal et al. [1].The frequency shift towards the higher side in Fig. 2 reveals the substitution of Cu 2+ ion into the Zn-O lattice [3]. SEM and EDS graphs (Fig. 3 and Fig. 4) show the hexagonal wurtzite crystal nature and Cu concentrations of the prepared samples respectively. XRD patterns (Fig. 7) for ZnO and CZO nanoparticles after annealed at 400 o C showed reflection peaks at (100), (002), (101), (102), (110), (103) and (112) indicating the hexagonal wurtzite crystal structure which is in accordance with SEM images (space group: P63mc (186) or C6v). The crystal growth orientation of ZnO and CZO nanoparticles produced the highest peak at 31.75 o for ZnO and at 31.82 o , 31.73 o , 31.85 o for 3% CZO, 5% CZO and 10% CZO nanoparticles respectively (Fig. 8). The strong (002) peak indicates that particles are grown along preferential orientation of [002] owing to small surface energy [4]. It is evident from the XRD spectra that there are no extra peaks corresponding to Cu, oxides of Cu or Cu related secondary and impurity phases which may be attributed to the incorporation of Cu ion into Zn lattice site rather than interstitial ones. Crystal size (Fig. 9), stress (Fig. 13), microstrain (Fig. 11), energy density (Fig. 12) and dislocation density (Fig. 10) of the synthesized nanoparticles were estimated using debye-Scherrer model, williamson-Hall model, uniform stress deformation model (USDM), uniform deformation energy density model (UDEDM), approximation method and size-strain plot method (SSP). Particle size reduces due to distortion of host ZnO lattice by foreign impurity Cu 2+ ions. Lattice strain increases due to increasing dislocation density. Substitute of Cu 2+ ions instead of Zn 2+ ions at the lattice also increases the lattice constant a (3.244777 to 3.247180) and c (5.199463 to 5.204330) value [5]. Nanoparticles don't give transmittance and they don't have enough surface area to give absorbance [6], so they reported diffused reflectance of about 77% for ZnO and 62%-64% for Cu doped nanoparticles. Bandgap was calculated from diffused reflectance data using Kubelka-Munk function. Conclusion: Cu doped ZnO nanoparticles were synthesized using chemical precipitation method. Al these 6 structural models were not reported together at any previous report and Cu doping concentration limit was reported below 6% at S. Muthukumaran et al. [7]. Minimum particle size was estimated from SSP that is 16.91 nm and maximum particle size was estimated as 52.92 nm from UDM. Peak shift due to doping indicates Cu 2+ ion incorporation into Zn lattice site. Particle size estimated from various structural models are in accordance with the SEM particle distribution. These prepared nanoparticles powder is suitable as a source material for thin film fabrication.

Zinc Oxide (ZnO) nanoparticles was synthesized by chemical precipitation method after aging for 7... more Zinc Oxide (ZnO) nanoparticles was synthesized by chemical precipitation method after aging for 72 hour using Zinc acetate (ZnC4H6O4) as the precursor material, Isopropanol (C3H8O) as solvent and Monoethanolamine (C2H7NO) as stabilizer. The effect of annealing temperature on composition and structural properties of ZnO nanoparticles was investigated. The nanoparticles synthesized under optimum conditions (deposition time, td =120 min, temperature = 60◦ C) showed good structural properties. The samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) before and after annealing. XRD data confirmed the hexagonal structure of ZnO nanoparticle. Different models were used to extract the micro structural parameters from the XRD data. Average size of the ZnO particles was found to be in the range 30 to 60 nm. The size distribution of ZnO crystalline was also observed from SEM images.
Keywords: ZnO Nanoparticles, Chemical precipitation method, Structural properties, XRD, SEM

Talks by Tasnim Kamal

EEE DAY Poster Presentation Competition 2015, 2015

CZTS is a new type of an absorber and abundant materials for thin film solar cells .Cadmium sulph... more CZTS is a new type of an absorber and abundant materials for thin film solar cells .Cadmium sulphide (CdS) is the n-type buffer layer of it and its band gap is 2.42 eV. Cadmium sulphide (CdS) buffer layer of CZTS solar cell was deposited on glass substrates by the Chemical Bath Deposition(CBD) method, using anhydrous cadmium Chloride(CdCl2) and thiourea (CS(NH2)2) as sources of cadmium and sulphur ions respectively. To find the optimum thickness various bath temperature and concentration of thiourea were varried. The influence of bath temperature and deposition time and [S]/[Cd] ratio in the solution on the structural, morphological, chemical composition and optical properties of these films were investigated . The films deposited under optimum conditions (Tb =80 ◦ C , td =70 min , [S]/[Cd] =3.5) were relatively well crystallized .

International Journal for Research in Applied Science and Engineering Technology (IJRASET), 2018

$Research paper thumbnail of Crystal Size and Strain Estimation of 10% Cu doped ZnO Nanoparticles using X-ray Diffraction Data$

2018 4th International Conference on Electrical Engineering and Information & Communication Technology (iCEEiCT), 2018

International Conference on Material Science and Semiconductor Devices (ICMSSD) 2018, 2018

EEE DAY Poster Presentation Competition 2015, 2015