NOPR Collection:

Novel methods to reduce leakage current in Si PIN photodiodes designed and fabricated with different dielectrics

2014-09-01T00:00:00Z

Title: Novel methods to reduce leakage current in Si PIN photodiodes designed and fabricated with different dielectrics Authors: Rao, Y P Prabhakara; Praveen, K C; Rani, Y Rejeena; Prakash, A P Gnana Abstract: The silicon PIN photodiodes were designed and fabricated in the conventional bipolar planar technology by using novel methods to reduce the leakage current. The new process steps like gettering, oxide stacking fault removing, ion implantation with suitable masking and improving shallow junction technology were implemented to fabricate PIN photodiodes of different active area such as 1 mm 1 mm, 2 mm 2 mm and 10 mm 10 mm. The performance of PIN photodiodes has been studied by measuring dark current, C-V characteristics and spectral response. The two different dielectrics such as silicon dioxide (SiO₂) and silicon nitride (Si₃N₄) with different thickness were used as anti-reflective coating (ARC). The electrical characteristics and spectral measurements exhibit that the photodiodes are highly sensitive with low leakage current. Page(s): 637-644

Dielectric relaxation studies of polyvinylpyrrolidone (PVP) and polyvinylbutyral (PVB) in benzene solutions at microwave frequency

2014-09-01T00:00:00Z

Title: Dielectric relaxation studies of polyvinylpyrrolidone (PVP) and polyvinylbutyral (PVB) in benzene solutions at microwave frequency Authors: Rawat, A; Mahavar, H K; Tanwar, A; Singh, P J Abstract: Microwave dielectric relaxation measurements on polyvinylpyrrolidone (PVP), polyvinylbutyral (PVB) and their binary mixture have been done in dilute solutions of benzene at 9.015 GHz at 303K temperature. The heterogeneous molecular interactions and intra-molecular rotations of these polymers in dilute solutions have been studied by comparing the evaluated values of average relaxation time (τ₀), relaxation times corresponding to overall molecular rotation (τ₁) and intra-molecular rotation (τ₂). The values of different dielectric parameters namely; static permittivity (є₀), dielectric constant (є'), dielectric loss (є") and optical permittivity (є_∞) have been determined for five different mole fractions of PVP-PVB. The dipole moment (μ) and free energy of activation ∆F_є were also calculated. It is observed that the value of μ decreases, whereas ∆F_є increases with the increase of mole fraction of PVP in the mixture. The higher values of the distribution parameter (α) indicate that besides the overall rotation, there is a large contribution of segmental reorientation and group rotation to the relaxation processes. Page(s): 632-636

Dielectric properties of spinel Co₃_-xMn_xO₄ (x = 0.1, 0.4, 0.7, and 1.0) ceramic compositions

2014-09-01T00:00:00Z

Title: Dielectric properties of spinel Co₃_-xMn_xO₄ (x = 0.1, 0.4, 0.7, and 1.0) ceramic compositions Authors: Meena, P L; Sreenivas, K; Kumar, Ravi Abstract: Cobalt manganese oxides Co₃_-xMn_xO₄(x = 0.1, 0.4, 0.7, and 1.0) multi-ferroic ceramic were prepared by conventional solid state technique to understand the effect of Mn substitution at Co site on the structural and dielectric properties. Single phase polycrystalline with a linear increase in the lattice parameter ‘a’ was observed without any structural change in cubic crystal symmetry with Mn substitution. The effect of Mn substitution on the dielectric constant (ε') and loss tangent (tan) was measured over a wide temperature range (150-450 K) and frequency range (100-900 kHz). A very weak frequency dispersion and small temperature dependence was observed in ε' and tan at low temperature, however, ε' and tan display a strong frequency and temperature dependency at higher temperature. The ε' shows a ferroelectric like transition and shift to lower temperature with Mn incorporation. The behaviour of tan shows dielectric relaxation and also shifts towards lower temperature with Mn incorporation. The ceramic compositions show universal dielectric response with temperature dependent exponent factor‘s’ and which fall in Jonscher’s range. Page(s): 625-631

Solar cells of Cu₂ZnSnS₄ thin films prepared by chemical bath deposition method

2014-09-01T00:00:00Z

Title: Solar cells of Cu₂ZnSnS₄ thin films prepared by chemical bath deposition method Authors: Subramaniam, E P; Rajesh, G; Muthukumarasamy, N; Thambidurai, M; Asokan, Vijayshankar; Velauthapillai, Dhayalan Abstract: Solar cells based on kesterite-type Cu₂ZnSnS₄ have been successfully fabricated on ITO substrates by cost effective chemical bath deposition method. The structural properties of the material have been studied using X-ray diffraction pattern and it confirms the formation of Cu₂ZnSnS₄ with kesterite structure. The surface topography has been studied using atomic force microscope and the rms roughness of the film was found to be 3.2 nm. The chemical constituents present in the prepared films have been identified using energy dispersive X-ray analysis. The optical band gap energy of CZTS thin film was found to be 1.5 eV which is quite close to the optimum value required for solar cell application. The power conversion efficiency of fabricated Cu₂ZnSnS₄ based solar cell is 1.34%. Page(s): 620-624

NOPR Collection:

Novel methods to reduce leakage current in Si PIN photodiodes designed and fabricated with different dielectrics

Dielectric relaxation studies of polyvinylpyrrolidone (PVP) and polyvinylbutyral (PVB) in benzene solutions at microwave frequency

Dielectric properties of spinel Co3-xMnxO4 (x = 0.1, 0.4, 0.7, and 1.0) ceramic compositions

Solar cells of Cu2ZnSnS4 thin films prepared by chemical bath deposition method

Dielectric properties of spinel Co₃_-xMn_xO₄ (x = 0.1, 0.4, 0.7, and 1.0) ceramic compositions

Solar cells of Cu₂ZnSnS₄ thin films prepared by chemical bath deposition method