Browsing by Author "C. Periasamy"

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Effect of post annealing on structural properties of ZnO thin films deposited by thermal evaporation technique
(2008) C. Periasamy; P. Chakrabarti; Rajiv Prakash
The thermal evaporation deposition technique was used to produce zinc oxide thin film onto p-type silicon substrate at room temperature. The prepared film was post annealed at different temperature from 400 to 800°C in O 2 ambient atmosphere for 20 minutes. The effect of post annealing temperature on the structural properties and surface morphological of ZnO thin films have been studied by XRD and AFM respectively. XRD analysis reveals that the prepared films were polycrystalline in nature with c-axis orientation. The optical band gap and resistivity of ZnO thin film were estimated using UV-Visible and four probe measurements respectively.
Electrical and optical characterization of ZnO based nano and large area Schottky contacts
(2011) C. Periasamy; P. Chakrabarti
Nanocrystalline ZnO thin films have been grown on glass substrates by thermal evaporation technique. The structural, morphological and optical properties of the thin film were investigated using X-ray diffraction, atomic force microscopy (AFM) and UV measurements respectively. The study revealed that ZnO nanoneedles consist of typical single crystalline ZnO with perfect needle shape and small surface roughness. The grown ZnO thin film was subsequently used to fabricate a metal-semiconductor-metal (MSM) ZnO photodiode with palladium (Pd) contact electrodes. The detector was successfully tested using the UV source operating at λ = 365 nm. The photoresponsivity of the detector is estimated to be 0.14 A/W. The device is expected to be used as a sensitive UV detector. © 2011 Elsevier B.V. All rights reserved.
Large-area and nanoscale n-ZnO/p-Si heterojunction photodetectors
(2011) C. Periasamy; P. Chakrabarti
The article reports the results of our experimental investigation on the effect of UV light on the characteristics of n-ZnO/p-Si heterojunction. c-Axis oriented zinc oxide (ZnO) films were deposited by thermal evaporation technique on p-type silicon (Si) substrates to form ZnO/Si heterojunctions. Both large-area and nanoscale heterojunction configurations were studied. The measured current-voltage characteristics in dark and illuminated conditions confirm the rectifying behavior of the heterojunctions and an excellent UV response. The responsivity values were measured to be of 0.18 and 0.12 A/W to UV light (365nm) for large-area and nanoscale heterojunctions, respectively. The values are comparable with those offered by other commercial UV detectors. The nanoscale heterojunction device can find applications in nanophotonics. © 2011 American Vacuum Society.