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Surface-type nonvolatile electric memory elements based on organic-on-organic CuPc-H_2Pc heterojunction

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Chinese Physics B 2015年第11期24卷 328-332页

作者： Khasan S.karimov Zubair Ahmad Farid Touati m.mahroof-Tahir m.muqeet Rehman S.Zameer Abbas Ghulam Ishaq Khan Institute of Engineering Science and Technology Center for Innovative Development of Science and New Technologies Department of Electrical Engineering College of Engineering Qatar University Department of Chemistry and Earth Sciences Qatar University

A novel surface-type nonvolatile electric memory elements based on organic semiconductors CuPc and H2Pc are fabricated by vacuum deposition of the CuPc and H2Pc films on preliminary deposited metallic （Ag and Cu） electrodes. The gap between Ag and Cu electrodes is 3040μm. For the current-voltage （I-V） characteristics the memory effect, switching effect, and negative differential resistance regions are observed. The switching mechanism is attributed to the electric-field-induced charge transfer. As a result the device switches from a low to a high-conductivity state and then back to a low conductivity state if the opposite polarity voltage is applied. The ratio of resistance at the high resistance state to that at the low resistance state is equal to 120-150. Under the switching condition, the electric current increases -- 80-100 times. A comparison between the forward and reverse I-V characteristics shows the presence of rectifying behavior.

关键词： heterojunction nonvolatile memory organic-on-organic CuPc H2Pc

Low temperature properties of organicinorganic Ag/p-CuPc/n-GaAs/Ag photoelectric sensor

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Science China(Technological Sciences) 2008年第2期51卷 153-161页

作者： Kh. S. karimov I. QAZI T. A. KHAN m. I. FEDOROV Physical Technical Institute of Academy of Sciences GIK Institute of Engineering Science and Technology State Technical University

A thin organic film of p-type semiconducting copper phthalocynanine (CuPc) was deposited by vacuum evaporation on an n-type GaAs single-crystal semiconductor substrate. The fabricated Ag/p-CuPc/n-GaAs/Ag sensor was carried through an ageing process to stabilize the parameters. Voltage-current characteristics and photoelectrical response of the sensor were investigated at a wide temperature range of 82 to 350 K. Photoelectric characteristics were measured under non-modulated filament-lamp illumination. It was observed that such sensor parameters as rectification ratio,threshold voltage,junction,shunt and series resistances,open-circuit voltage and short circuit current are temperature-dependent. It was found that wide-range voltage-current characteristics of the sensor may be de-scribed similarly to that of a Schottky barrier diode. Using the experimental data on voltage-current characteristics and absorbance of the CuPc films,the energy-band diagram of the p-CuPc/n-GaAs heterojunction was developed. It was shown that data obtained from simulation of an equivalent circuit of photoelectric sensor agreed with experimental results.

关键词： organic solar cell organic-inorganic heterojunction temperature dependent I-V characteristics

Synthesis of metal oxide composite nanosheets and their pressure sensing properties

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Journal of Semiconductors 2015年第2期36卷 18-23页

作者： muhammad Tariq Saeed Chani Sher Bahadar Khan Kh.S.karimov m.Abid Abdullah m.Asiri Kalsoom Akhtar Center of Excellence for Advanced materials Research (CEAmR) King Abdulaziz University Chemistry Department Faculty of Science King Abdulaziz University Interdisciplinary Research Center COMSATS Institute of Information Technology Physical Technical Institute of Academy of Sciences Division of Nano Sciences and Department of Chemistry Ewha Womans University

This study presents the synthesis of metal oxides composite nanosheets （oxides of cobalt, zinc and iron） and their pressure sensing properties. A transducer has been fabricated to directly measure the resistance- pressure and impedance-pressure relationships of pristine nanopowder. At the initial stage, a nanopowder sample of 10 mm diameter and 1 mm height was placed in the transducer and by applying pressure of up to 8.15 kN/m^2; the DC resistance and the impedance are reduced by 44% on average. It can be explained by the densification of the samples and a decrease in porosity due to the effect of pressure. It was also observed that the DC resistance increases with time and saturated within 8 min. It is considered that this phenomenon is based on the effect of displacement currents of bound charges. The dependences of the impedance phase （8） on frequency and pressure have also been investigated.

关键词： nanostructures oxides chemical synthesis optical properties electron microscopy

Humidity sensing properties of CU_2O-PEPC nanocomposite films

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Journal of Semiconductors 2012年第7期33卷 11-15页

作者： Kh.S.karimov m.Saleem Z.m.Karieva A.mateen m.Tariq Saeed Chani Q.Zafar GIK Institute of Engineering Sciences and Technology Topi-23640District SwabiKPKPakistan Physical Technical Institute of Academy of Sciences Rudaki Ave.33Dushanbe734025Tajikistan Government College of Science Wahdat RoadLahore-54570Pakistan Tajik Technical University Rajabov St.10Dushanbe 734000Tajikistan COmSATS Institute of Information Technology IslamabadPakistan

A blend of copper oxide nanopowder （Cu2O）, 3 wt.%, and poly-N-epoxypropylcarbazole （PEPC）, 2 wt.%, in benzol was drop-casted on glass substrates with pre-deposited surface-type silver electrodes for the fabrication of Cu20-PEPC nanocomposite thin films. The thicknesses of the Cu20-PEPC films were in the range of 10-13 μm. The effect of humidity on the electrical properties of the nanocomposite films was investigated by measuring the capacitance and dissipation of the samples at two different frequencies of the applied voltage： 120 Hz and 1 kHz. The AC resistance of the samples was determined from the dissipation values, and the DC resistance was measured directly. The effect of ageing on the humidity sensing properties of the nanocomposite was observed. After ageing, it was observed that at 120 Hz and 1 kHz, under a humidity of up to 86% RH, the capacitance of the cell increased by 85 and 8 times, and the resistance decreased by 345 and 157 times, accordingly, with respect to 30% RH conditions. It was found that with an increase in frequency, the capacitance and resistance of the samples decreased. It is assumed that the humidity response of the cell is associated with the diffusion of water vapors and doping of the semiconductor nanocomposite by water molecules.

关键词： cuprous oxide composite nano-powder poly-N-epoxypropylcarbazole humidity sensor

Effect of displacement on resistance and capacitance of polyaniline film

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Chinese Physics B 2011年第4期20卷 204-208页

作者： Khasan Sanginovich karimov muhammad Tariq Saeed Fazal Ahmad Khalid Syed Abdul moiz GIK Institute of Engineering Sciences and Technology Physical Technical Institute of Academy of Sciences Semiconductor Nano Processing Lab (SNPL) Department of Chemical and Material EngineeringHanyang University

This paper investigates the properties of displacement sensors based on polyaniline （PANI） films. About 1 wt% of PANI micropowder is mixed and stirred in a solution of 90 wt% water and 10 wt% alcohol at room temperature. The films of PANI axe deposited from solution by drop-casting on Ag electrodes, which are preliminary deposited on glass substrates. The thicknesses of the PANI films are in the range of 20 μm-80 μm. A displacement sensor with polyaniline film as an active material is designed and fabricated. The investigations showed that, on average, the AC resistance of the sensor decreases by 2 times and the capacitance accordingly increases by 1.6 times as the displacement changes in the range of 0 mm-0.5 mm. The polyaniline is the only active material of the displacement sensor. The resistance and capacitance of the PANI changes under the pressure of spring and elastic rubber, and this pressure is created by the downward movement of the micrometer.

关键词： polyaniline displacement sensor resistance and capacitance

Sensitivity enhancement of OD-and OD-CNT-based humidity sensors by high gravity thin film deposition technique

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Journal of Semiconductors 2015年第3期36卷 69-73页

作者： Kh.S.karimov Noshin Fatima Khaulah Sulaiman m.mahroof Tahir Zubair Ahmad A.mateen Ghulam Ishaq Khan Institute of Engineering Sciences and Technology Center for Innovative Development of Science and Technologies of Academy of Sciences Low Dimensional materials Research Centre (LDmRC) Department of Physics Faculty of Science University of Malaya Saint Cloud State University Department of Chemistry and Earth Sciences Faculty of materials Science and Engineering Institute of Space Technology

The humidity sensing properties of the thin films of an organic semiconductor material orange dye （OD） and its composite with CNTs deposited at high gravity conditions have been reported. Impedance, phase angle, ca- pacitance and dissipation of the samples were measured at 1 kHz and room temperature conditions. The impedance decreases and capacitance increases with an increase in the humidity level. It was found that the sensitivity of the OD-based thin film samples deposited at high gravity condition is higher than the samples deposited at low gravity condition. The impedances and capacitance sensitivities of the of the samples deposited under high gravity condition are 6.1 times and 1.6 times higher than the films deposited under low gravity condition.

关键词： orange dye sensor composite impedance capacitance

Resistive humidity sensor based on vanadium complex films

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Journal of Semiconductors 2014年第9期35卷 35-38页

作者： Kh.S.karimov m.Saleem m.mahroof-Tahir R.Akram m.T.Saeed Chanee A.K.Niaz GIK Institute of Engineering Sciences and Technology Topi-23640 District Swabi KPK Pakistan Physical Technical Institute of Academy of Sciences Rudaki Ave.33 Dushanbe 734025 Tajikistan Government College of Science Wahdat Road Lahore-54570 Pakistan Saint Cloud State University 720 Fourth Avenue South Saint Cloud MN 56301-4498 USA Center of Excellence for Advanced materials Research (CEAmR) King Abdul Aziz University Jeddah 21589 P.O.Box 80203 Saudi Arabia

A resistive-type relative humidity （RH） sensor based on vanadium complex （VO2（3-f[）） film is reported in this study. Gold electrodes were deposited on the glass substrates in a co-planar structure. A thin film of vanadium complex was coated as a humidity-sensing material on the top of the pre-patterned electrodes. The humidity-sensing principle of the sensor was based on the conductivity change of coated sensing element upon adsorption/desorption of water vapor. The resistance of the humidity sensor measured at 1 kHz decreased linearly with increasing the humidity in the range of 35%-70% RH. The overall resistance of the sensor decreases 11 times. An equivalent circuit for the VO2（3-fl） based resistive-type humidity sensor was developed. The properties of the sensor studied in this work make it beneficial for use in the instruments for environmental monitoring of humidity.

关键词： vanadium complex thin film humidity sensor resistance

Aluminium phthalocyanine chloride thin films for temperature sensing

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Chinese Physics B 2013年第11期22卷 629-633页

作者： muhammad Tariq Saeed Chani Abdullah m.Asiri Kh.S.karimov Atif Khan Niaz Sher Bhadar Khan Khalid.A.Alamry Center of Excellence for Advanced materials Research King Abdulaziz University Department of Chemistry Faculty of Science King Abdulaziz University GIK Institute of Engineering Sciences and Technology Physical Technical Institute Aini St. 299/1

This study presents the fabrication and temperature sensing properties of sensors based on aluminium phthalocyanine chloride （AlPcCl） thin films. To fabricate the sensors, 50-nm-thick electrodes with 50-μ gaps between them are deposited on glass substrates. AlPcCl thin films with thickness of 50–100 nm are deposited in the gap between electrodes by thermal evaporation. The resistance of the sensors decreases with increasing thickness and the annealing at 100 ℃ results in an increase in the initial resistance of sensors up to 24%. The sensing mechanism is based on the change in resistance with temperature. For temperature varying from 25 ℃ to 80 ℃, the change in resistance is up to 60%. Simulation is carried out and results obtained coincide with experimental data with an error of ±1%.

关键词： temperature sensor thin films annealing aluminium phthalocyanine chloride

Orange dye polyaniline composite based impedance humidity sensors

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Chinese Physics B 2013年第1期22卷 161-166页

作者： muhammad Tariq Saeed Chani Kh. S. karimov F. A. Khalid S. Z. Abbas m. B. Bhatty GIK Institute of Engineering Sciences and Technology Topi 23640 Khyber Pakhtunkhwa Pakistan Center of Excellence for Advanced materials Research (CEAmR) King Abdulaziz University Jeddah 21589 P.O. Box 80203 Saudi Arabia Physical Technical Institute Aini St. 299/1 Dushanbe 734063 Tajikistan

This study presents the fabrication and investigation （PANI） composite films. A blend of 3 wt.% OD with 1 of humidity sensors based on orange dye （OD） and polyaniline wt.% PANI was prepared in 1 ml water. The composite films were deposited on glass substrates between pre-deposited silver electrodes. The gap between the electrodes was 45 um. The sensing mechanism was based on the impedance and capacitance variations due to the absorption/desorption of water vapor. It was observed that with the increase in relative humidity （RH） from 30% to 90%, the impedance decreases by 5.2 × 10^4 and 8.8 × 10^3 times for the frequencies of 120 Hz and 1 kHz, respectively. The impedance-humidity relationship showed a more uniform change compared to the capacitance-humidity relationship in the RH range of 30% to 90%. The consequence of annealing, measuring frequency, response and recovery time, and absorption-desorption behavior of the humidity sensor were also discussed in detail. The annealing resulted in an increase in sensitivity of up to 2.5 times, while the measured response time and recovery time were 34 s and 450 s, respectively. The impedance-humidity relationship was simulated.

关键词： organic-organic composite humidity sensor polyaniline orange dye