Shaheed U. Shaikh

Polyelectrolyte multilayer-assisted fabrication of p-Cu2S/n-CdS heterostructured thin-film phototransistors

We demonstrate meticulous fabrication of p-Cu2S/n-CdS heterojunction thin films using a facile wet-chemical approach. Ion exchange of Cu+ with Cd2+ is a serious problem during preparation of Cu2S/CdS multilayered thin films. This issue was addressed by employing polyelectrolyte multilayers on the CdS surface, which completely prevented CdS corrosion, thereby allowing fabrication of heterostructured Cu2S/CdS films. The formation of polyelectrolyte multilayers is monitored using cyclic voltammetry. The heterostructured films are characterized by structure and morphology. We further employed these films as modified p-channel, p-Cu2S/n-CdS thin-film phototransistors, where n-CdS acts as the electron transporting and hole-blocking layer that extracts and grounds the photogenerated electrons. This device exhibited a significant increase in photocurrent density (>75 times), drift mobility (>87 times), and good linearity without having to apply gate voltage, when compared to its individual component device.

Wet chemically grown composite thin film for room temperature LPG sensor

We have synthesized thin film of zinc oxide-polyaniline (ZnO/PANI) composite using a simple wet chemical approach. As-synthesized ZnO/PANI composite thin film studied using different characterization techniques. The optical study reveals the penetration and interaction of PANI molecules with ZnO thin film. Prominent blue shift in UV-vis due to interaction between ZnO and PANI indicate presence of zinc oxide in polyaniline matrix. It is observed that ZnO thin film is not sensitive to LPG (liquefied petroleum gas) at room temperature. On the other hand ZnO/PANI composite thin film shows good response and recovery behaviors at room temperature.

Investigation on the effect of copper doping on CdS1-xSex thin films

ABSTRACT Here we report the generation of Cu2S nanoparticles within CdS0.8Se0.2 using cost effective chemical bath deposition technique on a glass substrate. The As-deposited CdS0.8Se0.2 films were doped with copper for different time intervals i.e. 20 sec, 60 sec and 100 sec, which shows an increase in band gap with an increase in doping time interval. XRD confirms the presence of hexagonal Cu2S phase with CdS0.8Se0.2 thin film after doping. Photovoltaic studies of prepared samples were investigated by I-V measurement system in dark and under illumination (100 W/cm2). I-V plot reveals the formation of a heterojunction between Cu2S and CdS0.8Se0.2.

Synthesis and characterization of CdS-polyelectrolyte-Bi2S3 thin film by SILAR

CdS-Polyelectrolyte-Bi2S3 was grown by cost effective successive ionic layer adsorption and reaction method (SILAR) on glass substrate. The polyelectrolyte used as a protecting layer for excessive ionic loss during the exchange reaction between the cation and anions of the reactants. Thin films was characterized for structural, morphological and an I-V characteristic. The X-ray diffraction pattern (XRD) pattern shows that, CdS-Polyelectrolyte-Bi2S3 thin films have mixed phase of hexagonal and orthorhombic crystal structures corresponding to CdS and Bi2S3 respectively. Scanning electron microscopy (SEM) corresponds deposition of the material along with the presence of bundle like shape is observed in thin film. The I-V measurement under dark and illumination to 100 mW/cm2 shows increase in photoconductivity.

Engineering of Wet Chemically Grown Nanostructured Zinc Oxide Thin Film by High Electronic Excitation

Thin films of ZnO are synthesized on ITO substrate using successive ionic layer adsorption and reaction (SILAR) technique. The as‐grown thin films were annealed at 250 °C (pristine) in vacuum atmosphere (10−2 Torr) for 1 h and further irradiated using 120 MeV Au9+ ions with different fluence 3×1012 and 5×1012 ions/cm2. These pristine and irradiated samples were studied for structural and optoelectronic properties. XRD study reveals better crystalline quality of film at 3×1012 ions/cm2 fluence. On the other hand, electrical resistivity of the films decreases from 13.44 Ω‐cm to 3.74 Ω‐cm with increase in irradiation fluence. Also it appears that irradiation does not affect absorption edge.