Singaperumal Singaperumal

Abstract: A textured Sb-doped a-Si film is synthesised using laser-assisted doping combined with texturing for a photovoltaic cell applictaion.The amorphous silicon films coated with Sb to a thickness of 200-300 nm are treated intially with a threshold laser fluence of 460 mJ/cm2 for dopant diffusion.To reactivate the dopant,the samples are retreated with a lower laser fluence of 230 mJ/cm2.The laser diffusion and dopant activation are performed by overlapping the laser spots to 90% of its size,so as to subsequently induce texture on the surface.Generation of polycrystalline textured peaks is confirmed with different characterization methods,such as SEM,Raman Spectroscopy,AFM,resistance and absorbance measurements.Treated samples show a crystalline peak of 521 cm-1 with Raman spectroscopy taken from the front and back of the sample.The n-type characteristics of the samples is confirmed through Hall effect measurements,which confirms also the efficient doping.Surface texture with a roughness parameter of 450 nm and improvement in photocondcutivity and absorbance spectrosocpy values are observed,which confirmes the improved photovolataic properties of the samples.

Abstract: The paper deals with synthesis of Sb doped ZnO nanowire by considering Si coated with Sb and Au as substrate using carbothermal evaporation method. The horizontally oriented Sb doped ZnO nanowires with a diameter of 1 μm synthesized at 900 °C, which is quite high as compared to the Pure ZnO nanowires generated without the influence of Sb at 900 °C. The nanowire synthesized at 900 °C showed a measurable lower angle of about 0.06° from XRD and suppression of A 1 T and E 1 (L0) modes in Raman spectroscopic, this confirms the incorporation of Sb in ZnO lattice. The strong exciton emission and weak deep-level emission from room temperature PL and Strong emission attributed to the radiant recombination from neutral–acceptor–bound exciton (A 0 X) peak accompanied by two strong and broad emission of donor acceptor pair (DAP) from low temperature PL, this confirms the use of Sb as an acceptor for ZnO.

Abstract: The paper deals with synthesis of Sb and Sb–Al co-doped ZnO nanowires using nanoparticle assisted pulsed laser deposition (NAPLD) by considering Sb as a catalyst. The mechanism of the growth initiation of nanostructures from the Sb droplets is analyzed at varying growth temperature. Nanowires and nanosheets of different orientation were synthesized. With ZnO:Al target and Sb coated Si as substrates, at a growth temperature of 750 °C, random oriented high density nanowires with a diameter of about 1 μm and a length up to a few tens of micrometer were synthesized. The suppression of A1T modes and E1(L0) modes from Raman spectroscopy confirming that depletion of oxygen vacancies. XPS analysis confirming that the Sb would substitute for Zn(Sbzn) instead of oxygen Al–O bonds, leading to excess of oxygen, neutralizing the oxygen vacancies. The Sb–Al co-doped nanowires annealed at 650 °C showed a strong UV emission and reduction in visible emission as compared to the Sb–Al co-doped nanowires annealed at 450 °C. This confirms that the Sb–Al co-doped posses high stoichiometric nature, good structural and optical properties. To investigate the p-type conductivity of the Sb–Al co-doped nanowires, a homo p–n junction was prepared by synthesizing Sb–Al co-doped ZnO nanowires on the pure ZnO surface. The I–V characteristics of the homo P–N junction were investigated and a rectifying behavior was observed confirming the formation of p-type. Hence the Sb mono-doped and co-doped ZnO nanowires synthesized by using Sb as catalyst posses good structural and optical properties with good crystallization quality and high stoichiometry nature, hence it is highly suitable for light emitting device applications.