Investigation of morphology, electrical behavior (AC and DC) and CO2 gas sensitivity of porous silicon deposited with nanolayers of bromo aluminum phthalocyanine
Applied Physics Division, Physics Department, Tarbiat Moallem University, 43 Mofateh avenue, Tehran, Islamic Republic of Iran
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Revised: 6 April 2012
Accepted: 13 April 2012
Published online: 25 May 2012
The AC and DC electrical properties of sandwich devices fabricated with silicon (Si), porous silicon (PSi) and nanolayers of bromo aluminum phthalocyanine with aluminum electrodes (Al/Si/Al, Al/Si/PSi/Al, Al/Si/BrAlPc/Al and Al/Si/PSi/BrAlPc/Al) were examined over the voltage, frequency and temperature range of 0–11 mV, 102–105 Hz and 303–423 K respectively. Morphology of the samples was studied via scanning electron microscope (SEM) images and X-ray diffraction (XRD) micrographs. Capacitance is practically independent of frequency (f) in the range of 102–104 Hz, whereas it is extremely frequency dependent for f > 104 Hz. Dissipation factor decreased with increasing frequency to a minimum value and increased noticeably thereafter. Capacitance and dissipation factor are almost independent of temperature; capacitance increases with increasing temperature for T > 380 K. The AC electrical behavior of sandwich devices has been shown to be in agreement with the model of Goswami and Goswami. According to our data the Al contact in sandwich devices is of ohmic type and the tunneling mechanism is applicable in explaining the DC conduction process. The Al/Si/PSi/BrAlPc/Al device, compared to other devices, exhibits the highest sensitivity to CO2.
© EDP Sciences, 2012