Effect of humidity on copper phthalocyanine films

Effect of humidity on copper phthalocyanine films deposited at different gravity conditions Khasan S. Karimov Centre for Innovative Development of Science and Technologies of Academy of Sciences, Dushanbe, Tajikistan and GIK Institute of Engineering Sciences and Technology, Topi, Pakistan

Zubair Ahmad Department of Electrical Engineering, College of Engineering, Qatar University, Doha, Qatar

Noshin Fatima and Muhammad Mansoor Ahmed Department of Electrical Engineering, Capital University of Science and Technology (CUST), Islamabad, Pakistan, and

Muhammad Abid

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Interdisciplinary Research Center, COMSATS Institute of Information Technology, Wah Cantt, Pakistan Abstract Purpose – The paper aims to study the effects of humidity on the electrical properties of copper phthalocyanine (CuPc) thin films deposited at different gravity conditions. Design/methodology/approach – Surface-type samples were fabricated on glass substrates with preliminary-deposited copper electrodes. The CuPc solution was prepared in benzene. The thin films of CuPc were deposited on these substrates at diverse gravity conditions by drop-casting and centrifugation at 1 ⫻ g and 70 ⫻ g, respectively. Impedance and capacitance of the fabricated devices were measured against the different relative humidity ranging from 32 to 98 per cent. Findings – The impedance and the capacitance of the CuPc film were found to be dependent on the ambient humidity levels (32-98 per cent) and the gravity conditions (1 ⫻ g and 70 ⫻ g) opted during the fabrication process. Research limitations/implications – The centrifugation technique can potentially be used in the instrumentation industry for the fabrication of humidity sensors. Practical implications – The results of the investigations can potentially be used in the instrumentation and optoelectronics industry for the fabrication of humidity sensors. Originality/value – CuPc films were deposited from a solution in benzene using drop-casting and centrifugation. The electrical properties of the films were found to be dependent on film fabrication conditions and ambient humidity levels. Growth-dependent electrical properties of the CuPc films can be explained by considering their structure. Keywords Colorant, Humidity, High gravity, Centrifugation, Copper phthalocyanine, Drop-casting Paper type Research paper

Introduction

are found suitable for centrifugal processing (Regel and Wilcow, 2000; Wilcox and Regel, 1996). The properties of devices based on metallophthalocyanines grown by the organic molecular beam deposition (OMBD) technique were investigated by Colesniuc (2011). It was reported by Colesniuc that the conductivity of the grown films increases exponentially with temperature, whereas it decreases exponentially with increasing the thickness of the films. Applications of copper phthalocyanine (CuPc) include

Phthalocyanines are used as pigments in automotive paints, printing inks, blue/cyan dyes for textiles and the paper industry. Because of their versatile applications, phthalocyanines have been the focus of interest in organic semiconductor and photosensitive industries as well. It is an established fact that the structures and properties of organic semiconductors are highly dependent upon their processing technology (Gutman and Lyons, 1981; Gutman et al., 1983). Generally, organic materials have a high molecular weight and strong intramolecular but weak van der Waal’s intermolecular bonding. Because of these properties, organic semiconductors

The authors are thankful to Capital University of Science and Technology (CUST) and Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Pakistan, for supporting this work. Received 23 November 2014 Revised 4 April 2015 9 July 2015 23 September 2015 30 January 2016 23 February 2016 7 March 2016 29 March 2016 17 April 2016 Accepted 21 May 2016

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Pigment & Resin Technology 46/1 (2017) 64 –70 © Emerald Publishing Limited [ISSN 0369-9420] [DOI 10.1108/PRT-11-2014-0105]

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Effect of humidity on copper phthalocyanine films

Pigment & Resin Technology

Khasan S. Karimov et al.

Volume 46 · Number 1 · 2017 · 64 –70

Figure 1 Molecular structure of CuPc

photovoltaic cells, paint, ink, etc. Organic thin-film transistors were also fabricated using CuPc dye with the standard vacuum evaporation method (Wu et al., 2013). These transistors had a five-layered structure comprising of Au (source)/CuPc/Al (gate)/CuPc/Au (drain) and exhibited a relatively good performance. Dependence of electrical properties of CuPc and metal-free phthalocyanine (H2Pc) bulk heterojunction structures under varying illumination conditions was also studied by Farooq et al. (2015). A comparative analysis of current–voltage (I-V) characteristics in dark and under illumination showed that the devices were sensitive toward visible light. Their absorption spectra exhibit photosensitivity in the wavelength ranging from 200 to 850 nm. Touka et al. (2013) reported preparation and characterization of CuPc nanocrystals embedded into the polymer host and investigated optical absorption spectra of the grown films. A comparison of electric and optical properties of an organic semiconductor clearly demonstrates an obvious correlation between the activation energy measured by the conductivity– temperature or by the absorption spectra (Brutting et al., 2012). Similarly, the color of an organic material is dependent on its band gap or activation energy. Encouraged from these characteristics, the colorants films were fabricated especially in an unconventional environment, for example at high gravity conditions, to explore their potential use in the organic semiconductor industry. Previously, we reported the heterojunctions fabricated under high gravity using p-type Si and thin films of poly-N-epoxypropylcarbazole (PEPC) doped with tetracyanoquinodimethane (Ahmed et al., 2004). The PEPC films were grown on Si wafers at different gravity conditions (i.e. 1 ⫻ g, 123 ⫻ g, 277 ⫻ g and 1,107 ⫻ g). It was observed that the grown organic polymer films had uniform surface morphology and good adhesiveness on Si substrate. The I-V characteristics of the fabricated hybrid structures were evaluated as a function of temperature ranging from 20°C to 60°C. It was found that all the samples were p-p isotype heterojunctions. Rectification ratio, threshold voltage, reverse saturation current and junction resistance of the fabricated junctions were evaluated at different temperatures. Later on, a theoretical model has been proposed by Hu and Chen (2015) by developing a relationship that quantitatively linked the centrifugal time with centrifugal conditions to fabricate high-quality photonic crystals. In this paper, in continuation of our efforts pertaining to humidity and temperature sensors (Karimov et al., 2008, 2012), we are presenting humidity-dependent electrical properties of CuPc thin films deposited at different gravity conditions (1 ⫻ g and 70 ⫻ g) using the centrifugation technique.

broad absorption spectra in visible and partly in ultraviolet and infrared wavelength regimes (Forrest and Xue, 2004). Fabrication Thin films of CuPc were deposited from a 5 wt. per cent solution in benzene at normal (1 ⫻ g) and at high (70 ⫻ g) gravity conditions. At 1 ⫻ g, the films were deposited by drop-casting, whereas at 70 ⫻ g, the films were deposited using a table-top centrifugation apparatus (Model: HETTICH EBA-20 S). The acceleration (a) was calculated using equation (1) as follows: a ⫽ R␻2

(1)

where R is the radius and ␻ is the angular velocity. Figure 2 shows the schematic diagram of the sample. Using the vacuum thermal evaporation technique, 200-nm thick Cu films were deposited. The CuPc powder was dissolved in benzene at room temperature. Glass substrates with pre-deposited Cu electrodes having inter-electrode spacing 30-40 ␮m were placed inside a glass tube mounted in the centrifugal machine. The diameter and length of the glass tube were 12 and 95 mm, respectively. During deposition of the films, the centrifugal machine speed was set at 5,000 rpm. For each experiment, two symmetrically installed glass tubes filled with the solution of equal volume of 0.5 ml were used. During the centrifugation process, the solution was allowed to evaporate at room temperature and atmospheric pressure without any additional heating. The process of film deposition was completed in 30-50 min, and the thickness of the films varied from 6 to 12 ␮m. Impedance and capacitance measurements of the fabricated devices were carried out using LCR meter MT 4090 configured at 1 kHz and 1 V. The in-situ humidity was measured using humidity/temperature meter TECPEL 322.

Results and discussion Figure 3 shows atomic force microscope (AFM) images of the CuPc films deposited at normal (1 ⫻ g) and high (70 ⫻ g) gravity conditions. The figure clearly shows that films grown at 70 ⫻ g offered smoother surface morphology than films grown at 1 ⫻ g. Impedance– humidity and capacitance– humidity relationships for CuPc films deposited at 1 ⫻ g and 70 ⫻ g are shown in Figure 4(a) and (b), respectively. Experimental results presented in Figure 4 show that films deposited at 1 ⫻ g exhibited a maximum of 45.4 per cent (⌬Z 100 per cent/Z) change in its impedance value, whereas in capacitance, the maximum observed

Experimental Materials For thin film deposition, commercially produced (Aldrich) CuPc (C32H16CuN8) powder was used. Figure 1 shows the molecular structure of CuPc. Its molecular weight is 576.08, and it is very stable (Kumar and Ghosh, 2002). It is a photosensitive semiconductor (Hiesgen et al., 2000) and has 65




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Figure 3 AFM images of the CuPc films deposited from the benzene solution Figure 4 Impedance– humidity and capacitance– humidity relationships of CuPc films 3.2 65 3.1

Impedance (MΩ)

60

3.0

Impedance Capacitance

55

2.9

50

2.8

45

2.7 2.6

40

Capacitance (pF)

2.5 35 2.4 30

40

50

60

70

80

90

100

Relative Humidity (%)

(a) 70

2.8

65 2.7 60

change was 26.5 per cent (⌬C 100 per cent/C). On the other hand, films deposited at 70 ⫻ g showed 42.2 and 15.7 per cent maximum change in their impedance and capacitance values, respectively. The impedance (Z) of the samples can be represented by the parallel combination of a resistor (R) and a capacitor (C). From circuit point of view, the magnitude of Z caused by sample resistance and capacitance can be represented as follows (Dally et al., 1993): Z⫽

R (1 ⫹ j␻RC)

Impedance Capacitance

55

2.6

50 2.5

45

Capacitance (pF)

Impedance (MΩ)


Figure 2 Schematic diagrams of the sample

40 2.4 35 30

40

50

60

70

80

90

100


(b) Notes: (a) Deposited at 1 × g; (b) deposited at 70 × g

(2)

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Variation in impedance because of the varying values of ambient humidity can be associated with adsorption and absorption of water molecules by the CuPc films. As a result of these processes, permittivity of the organic material increases, this in return increases the capacitance of the films, as shown in Figure 4(a) and (b). At the same time, because of the displacement currents related to the movement of bound charges of water molecules, the resistance of the samples may decrease. Finally, as per equation (2), the impedance of the samples decreases because of the increase of the capacitance and decrease of resistance as a function of ambient humidity as observed experimentally. It is a well-known fact that the value of the capacitance depends on the polarizability of the material, which has several basic sources, that is dipolar ␣dip, ionic ␣i, and electronic ␣e polarizability (Omar, 2002). In this case, ␣dip seems to play a dominating role because of the presence of water dipoles absorbed by CuPc, whereas ␣e is an universal phenomenon and arises because of the relative displacement of the orbital electrons. It is also assumed that CuPc molecules, after interacting with water molecules, may form charge-transfer complexes which as a result originate ␣i. Thus, the total polarizability which could affect the electrical response of CuPc films would be the sum of all the three components discussed hitherto. It is assumed that the dielectric permittivity of the CuPc increases because of adsorption and absorption of water molecules, which have a higher dielectric permittivity value. The absorption takes place by the diffusion process through the surface of the CuPc films. This increases the capacitance value of the sample. Further, the presence of displacement current caused by the water molecules could also be a source of increased capacitance and decreased resistance values. Moreover, there is also a possibility of CuPc films doping by the absorbed water molecules which as a result will increase the polarizability as well as the concentration of free charges. Both the processes, in return, will enhance the capacitance on one hand and decrease the resistance of the sample on the other hand (Boguslavsky et al., 1968). For organic semiconductor humidity sensors, impedance– humidity and capacitance– humidity characteristics were simulated by Saeed et al. (2010). Their simulation was based on Clausius–Mossotti relationship (Omar, 2002):

where CH represents the capacitance under humid condition and Cn represents capacitance at normal conditions. ⌬RH represents a change in relative humidity (⌬RH ⫽ H⫺H0; initial relative humidity H0 ⫽ 32 per cent) and k is a humidity capacitive factor. For CuPc, the relative permittivity is assumed to be 4 (Yan et al., 2010). The value of k determined by the above expression at ⌬RH ⫽ 66 per cent and Nn␣n was determined from equation (3). At maximum humidity, experimental value of CH/Cn was equated to the theoretical value and it was found that k ⫽ 0.0858. Figure 5 shows the comparison of experimental and simulated capacitance versus relative humidity for CuPc samples fabricated at 1 ⫻ g and 70 ⫻ g. It can be seen from the figure that the simulated data comply, with a reasonable accuracy, to the experimental characteristics. For simulation of relative impedance vs humidity characteristics, we have proposed a simplified expression as given below:

Nn␣n ␧⫺1 ⫽ ␧⫹2 3␧°

冉ZZ 冊 ⫽ ␥Exp冋⫺ HH 册 0

冋冋

Normalized Capacitance

1.25

册

2Nn␣n(1 ⫹ k⌬RH) 3␧0 Nn␣n(1 ⫹ k⌬RH) 1⫺ ␧ 3␧0

册

Experimental 1g Simulated 1g Experimental 70g Simulated 70g

1.20 1.15 1.10 1.05 1.00 30

40

50

60

70

80

90

100


Figure 6 Comparison of relative experimental and simulated impedance of the CuPc films deposited at 1 ⫻ g and 70 ⫻ g with respect to relative humidity

(3)

1⫹

(5)

0

Figure 5 Comparison of relative experimental and simulated capacitance of the CuPc films deposited at 1 ⫻ g and 70 ⫻ g with respect to relative humidity

where ␧ is the relative permittivity, Nn is the concentration of water molecules at normal conditions, ␣n is the polarizability of CuPc due to absorption of water molecules at usual conditions and ␧o is the permittivity of free space. Considering the proportionality of capacitance with permittivity, we can use the expression presented in Shah et al. (2008), Ahmad et al. (2008) and Saeed et al. (2010):

CH ⫽ Cn

2

where ␥ is a fitting variable. The simulated impedance– humidity relationship in comparison with the experimental results is shown in Figure 6. The simulated capacitance and impedance results both for 1 ⫻ g and 70 ⫻ g samples offer reasonable conformity to the experimental data, as evident from Figures 5 and 6. The

1.0

Normalized Impedance



(4)

0.9 0.8

Experimental 1g Simulated 1g Experimental 70g Simulated 70g

0.7 0.6 0.5 30

40

50

60

70

80

Relative humidity (%)

67

90

100




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References


discrepancy in the observed and simulated data of Figures 5 and 6 could be associated with the fact that films grown at different gravity conditions may have different structures and compositions with varying percentage of solvent molecules. Sensitivity (S) of CuPc-based humidity sensors can be assessed using the following equations (Dally et al., 1993): S(Z) ⫽

⌬Z ⌬RH

(6)

S(C) ⫽

⌬C ⌬RH

(7)

Ahmad, Z., Sayyad, M.H. and Karimov, K.S. (2008), “Capacitive hygrometers based on natural organic compound”, JOAM-RC, Vol. 2 No. 8, pp. 507-510. Ahmed, M.M., Karimov, K.S. and Moiz, S.A. (2004), “Temperature-dependent I-V characteristics of organic-inorganic heterojunction diodes”, IEEE Transactions on Electron Devices, Vol. 51 No. 1, pp. 121-126. Boguslavsky, S. and Vannikov, V.V. (1968), “Organic semiconductors”, Moscow, s.n. Brutting, W. and Chihaya, A. (2012), Physics of Organic Semiconductors, 2nd ed., Vch Publishers, New York, NY, s.l. Colesniuc, C.N. (2011), “Metallophthalocyanine thin films: structure and physical properties”, PhD thesis, University San Diego, California. Dally, J.W., Riley, W.F. and Mc-Connell, K.G. (1993), Instrumentation for Engineering Measurements, Second Edition, John Wiley & Sons, New York, NY. Farooq, A., Karimov, K.H.S., Ahmed, N. and Usman, M. (2015), “Copper phthalocyanine and metal free phthalocyanine bulk heterojunction photodetector”, Physica B: Condensed Matter, Vol. 457, pp. 17-21. Forrest, S.R. and Xue, J. (2004), “Carrier transport in multilayer organic photodetectors: I, effects of layer structure on dark current and photoresponse”, Journal of Applied Physics, Vol. 95 No. 4, pp. 1859-1868. Gutman, F. and Lyons, L.E. (1981), Organic Semiconductors, Part A, Robert E. Krieger Publishing Company, Malabar, Florida. Gutman, F., Keyzer, H. and Lyons, L.E. (1983), Organic Semiconductors, Part B, Robert E. Krieger Publishing Company, Malabar, FL. Hu, C. and Chen, Y. (2015), “Uniformization of silica particles by theory directed rate-zonal centrifugation to build high quality photonic crystals”, Chemical Engineering Journal, Vol. 271 No. 3, pp. 128-134. Hiesgen, R., Rabisch, M., Bottcher, H. and Meissner, D. (2000), “STM investigation of the growth structure of CuPc films with submolecular resolution”, Solar Energy Materials and Solar Cells, Vol. 61 No. 4, pp. 73-85. Karimov, K.S., Khan, I.Q., Khan, T.A. and Draper, P.H. (2008), “Humidity and illumination organic semiconductor copper phthalocyanine sensor for environmental monitoring”, Environmental Monitoring and Assessment, Vol. 141 Nos 1/3, pp. 323-328. Karimov, K.S., Khalid, F.A., Tariq Saeed Chani, M., Mateen, A., Asif Hussain, M. and Maqbool, A. (2012), “Carbon nanotubes based flexible temperature sensors”, Optoelectronics and Advanced Materials – Rapid Communications, Vol. 6 Nos 1/2, pp. 194-196. Kumar, A. and Ghosh, S. (2002), “Schottky energy barrier and charge injection in metal/CuPc/metal structure”, Applied Physics Letters, Vol. 80 No. 25, pp. 4840-4842. Omar, M.A. (2002), Elementary Solid State Physics: Principles and Applications, Pearson, Buona Vista. Parfeniev, R.V., Regel, L.L. and Astronautica, A. (2001), “Gravity application to anisotropic semiconductor materials”, High-Microgravity Conditions, Vol. 48 Nos 2/3, pp. 163-168.

where ⌬Z, ⌬C and ⌬RH are the changes in impedance, capacitance and relative humidity, respectively. Table I shows the maximum average values of S(Z) and S(C) for CuPc samples deposited at 1 ⫻ g and 70 ⫻ g. It is evident from Table I that CuPc films deposited at high gravity are less sensitive to the varied humidity conditions as compared to the films deposited at 1 ⫻ g. Presently, researchers are working not only in the area of high gravity processing of semiconductor materials but also in microgravity-based fabrication. In the study by Parfeniev et al. (2001), the properties of tellurium, Te–Se and Te80Si20 crystals grown under microgravity level and up to 10 ⫻ g were discussed. In general, the gravity conditions have an influence on defects distribution, conductivity and Hall effect mobility of the grown film.

Conclusions CuPc thin films were deposited at different gravity conditions (1 ⫻ g and 70 ⫻ g) from a solution in benzene by using drop-casting and centrifugation. Variation in impedance and capacitance as a function of ambient humidity levels was assessed. It was noted that impedance of CuPc thin films decreases, whereas their capacitance increases with increasing values of ambient humidity. Samples fabricated at 1 ⫻ g exhibited a maximum change of 45.4 and 26.5 per cent in their impedance and capacitance values, respectively, whereas samples grown at 70 ⫻ g demonstrated a maximum change of 42.2 and 15.7 per cent in their impedance and capacitance values, respectively. The observed response was also simulated, and a plausible explanation was presented. It was demonstrated that the humidity-dependent electrical performance could be associated both with increased polarization and increased doping concentration caused by absorbed water molecules. It was further shown that CuPc films can potentially be used as a humidity-sensing material whose sensitivity would be dependent on the chosen fabrication parameters. Table I Impedance S (Z) and capacitance S (C) sensitivities of the CuPc samples deposited at 1 ⫻ g and 70 ⫻ g No.

Semiconductor

1. 2.

CuPc CuPc

Deposition

S (Z), M⍀/%

S (C), pF%

1⫻g 70 ⫻ g

0.441 0.421

0.010 0.005

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Regel, L.L. and Wilcow, W.R. (2000), Processing by Centrifugation, Clarkson University, Potsdam, New York, NY, s.n. Saeed, M.T., Khalid, F.A., Karimov, K.S. and Shah, M. (2010), “Organic Cu/Cellulose/ PEPC/Cu Humidity Sensor”, JOAM-RC, Vol. 4 No. 6, pp. 888-892. Shah, M., Sayyad, M.H. and Karimov, K.S. (2008), “Fabrication and study of Nickel Phthalocyanine based surface type capacitive sensors”, World Academy of Science, Engineering and Technology, Vol. 43 No. 1, pp. 392-395. Touka, N., Benelmadjat, H., Boudine, B., Halimi, O. and Sebais, M. (2013), “Copper phthalocyanine nanocrystals embedded into polymer host: preparation and structural characterization”, Journal of the Association of Arab Universities for Basic and Applied Sciences, Vol. 13 No. 1, pp. 52-56. Wilcox, W.R. and Regel, L.L. (1996), “Centrifugal materials processing”, Proceedings of the Third International Workshop on Materials Processing at High Gravity, Clarkson University, Potsdam, NY. Wu, B., Wang, D. and Yang, Y. (2013), Device Operation of Organic Semiconductor Copper Phthalocyanine Thin Film Transistor, Harbin, 2nd International Conference on Measurement, Information and Control (ICMIC), Vol. 2013, pp. 206-208. Yan, D., Wang, H. and and Du, B. (2010), Introduction to Organic Semiconductor Heterojunctions, John Wiley & Sons, Fusionopolis.

ISESCO). His research interests include electrophysical properties of organic semiconductors, organic semiconductor devices (sensors and solar cells), materials processing at high gravity conditions (thin films) and use of renewable energy resources. He is a member of the Inventor of USSR, Member of the Society of Tajikistan Inventors, Expert of Tajikistan Academy of Sciences on Renewable Energy Resources, Laureate of Tajikistan Academy of Sciences Prize, 1980, Laureate of Competition “Best Inventor – 1997” in Tajikistan, IEEE. Zubair Ahmad works as a Researcher at Center for Advanced Materials (CAM), Qatar University, Doha, Qatar. He received his MS degree (Engineering Sciences) in 2008 from Ghulam Ishaq Khan Institute of Engineering Sciences and Technology, Pakistan, and PhD degree (Applied Physics) in 2011 from the same institute. His current research interests are renewable energy-materials besides organic non-volatile memories, organic sensors and organic smart materials. Zubair Ahmad is the corresponding author and can be contacted at: [email protected] Noshin Fatima is a full-time PhD student in Electronics Engineering at Muhammad Ali Jinah University, Islamabad, Pakistan. She has done her Masters in Electronics Engineering from Ghulam Ishaq Khan Institute, Topi, Swabi, KPK, Pakistan. She earned BS in Electronics Engineering from Comsats Institute Abbotabad, KPK, Pakistan. She has published journal and conference papers. She had done research projects with Khasan S. Karimov (in Masters and PhD) and Muhammad Mansoor Ahmed (in PhD) on high gravity depositions, electrochemical cells and sensors. Her research interests include electrophysical properties of organic semiconductors, organic semiconductor devices (sensors and solar cells), materials processing at high gravity conditions (thin films), use of renewable energy resources and making cheap devices. She is a member of PEC. She earned a PEC merit-based scholarship at the Master’s level and now a PhD scholarship from Muhammad Ali Jinnah University, Islamabad.

Further reading Boming, W., Dongxing, W. and Yang, Y. (2013), “Device operation of organic semiconductor copper phthalocyanine thin film transistor”, Measurement, Information and Control (ICMIC), 2013 International Conference, Harbin, pp. 206-208. Gregory, P. (2000), “Industrial applications of phthalocyanines”, Journal of Porphyrins and Phthalocyanines, Vol. 4 No. 4, pp. 1099-1409. Tahir, M.M. and Karimov, K.S. (2009), “Fabrication of heterojunctions and current-voltage characteristics of vanadium coordination compounds”, Journal of Optoelectronics and Advanced Materials, Vol. 11 No. 1, pp. 83-88.

Muhammad Mansoor Ahmed received his PhD degree in Microelectronics from the University of Cambridge, UK. He has been associated with academia at various levels for the past 20 years and, currently, is a professor in the Department of Electronic Engineering at Mohammad Ali Jinnah University, Islamabad, where he is also holding the post of Executive Vice President of the University. He is a chartered engineer from UK and also a fellow of Institution of Engineering and Technology, UK. He was awarded the title of European Engineer (Eur. Ing). in 2002 by the European Federation. He is a senior member of the Institution of Electrical and Electronic Engineering, USA. He enjoys lifetime membership of IEEE Electron Devices and IEEE Microwave Theory and Technique societies, USA. He has authored more than 100 research papers in the field of microelectronics, microwave MESFETs and HEMTs, Electromagnetics and RF Engineering. His ISI research impact factor is 50⫹ with H & i10 factors 13 and 18, respectively. He has more than 540 research citations, and based on his research contributions, he was awarded a gold medal in the field of Engineering and

About the authors Khasan S. Karimov is a Foreign Professor at the Faculty of Electronic Engineering of GIK Institute, Pakistan. He received his Doctor of Physical Mathematical Sciences degree from the Department of Heat Physics, Tashkent, Uzbekistan, 1994, and a PhD from the Physical Technical Institute, S.-Peterburg, USSR, 1982. He received his Engineering degree at the Electrotechnical Institute of Communication, Tashkent, USSR, 1971. His research projects comprised microhydropower plant, photovoltaic system, solar biogas digester (funded by Pakistan Science Foundation), investigation of electrical properties of organic semiconductor sensors (funded by Higher Education Commission of Pakistan), biogas digester, micro-hydropower plant, micro-hydropower plant (funded by NGO, Almaty) and solar energy utilization (funded by 69




Volume 46 · Number 1 · 2017 · 64 –70

Technology by the Pakistan Academy of Sciences in 2008. He holds the IEEE technical activities chair and has rendered services as an organizer, session and general chairs of several IEEE International Conferences.

include renewable energy systems, water and sediment flow simulations, welding simulations, bolted flanged pipe joints, product design and optimization and structural design engineering. He has been awarded the Pakistan Academy of Sciences Gold Medal, Best Researcher and Best Teacher Award by HCE Pakistan, Best Research Award by IMechE and several others.


Muhammad Abid is a Professor and the Director of Interdisciplinary Research Center at COMSATS Institute of Information Technology, Pakistan. His research interests

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