Sheeja Krishnan

Effect of 8 MeV electron irradiation on the performance of CSS grown CdTe/CdS solar cells

The results of investigations carried out on the effect of electron irradiation on the electrical properties of CdTe/CdS solar cells prepared by close spaced sublimation (CSS) are presented in this paper. The solar cells were characterized using current–voltage (I–V) measurements under dark and air mass (AM) 1.5 illumination conditions. They were also characterized by capacitance measurements at various frequencies. The cells were exposed to graded doses of electrons up to 100 kGy. The effect of electron irradiation on the solar cell parameters such as short circuit current (Isc), open circuit voltage (Voc), fill factor (FF), conversion efficiency (η), saturation current (Io) and ideality factor (n) were studied. Only small changes in the cell parameters were observed after electron irradiation. Since the observed changes in the cell parameters were not remarkable up to an electron dose of 100 kGy, CdTe/CdS solar cells seem to be stable under electron irradiation.

Electrical Properties of RF Sputtered CdTe/CdS Thin Film Solar Cells

The charge transport properties of CdTe/CdS solar cells deposited by radio frequency (RF) sputtering have been investigated and presented in this article. The temperature dependent current-voltage characteristics of the devices under dark condition were carried out in the temperature range 240-340 K. The capacitance of the devices at various frequencies was also investigated. procedures and both CdTe and CdS films were deposited using RF sputtering technique. The thickness of the films was approximately 2.0 μm for CdTe and 0.13 μm for the CdS film. The CdTe/CdS heterojunction was vapor chloride treated at 390 °C for 30 minutes under a flow of dry air. Pseudo ohmic contact to CdTe was obtained by vacuum evaporating 3 nm of Cu followed by 50 nm Au. The Cu diffusion was achieved by annealing the contacts at 150 °C for 35 minutes.

Measurement of Variation of Minority Carrier Lifetime in 8 MeV Electron Irradiated c-Si Solar Cells Using RRT Method

The variation of minority carrier lifetime in c-Si solar cells due to the irradiation of 8 MeV electrons of various doses ranging from 5 to 100 kGy was studied. The minority carrier lifetime and diffusion length of c-Si solar cells were determined before and after irradiation using the reverse recovery transient (RRT) method. The minority carrier lifetime is found to decrease with increasing electron dose, which is interpreted as due to the creation of non-radiative recombination centers which affects the diffusion current. The minority carrier diffusion length decreases exponentially with electron dose. The reduction in diffusion length due to electron irradiation will reduce the conversion efficiency of solar cells.

Dose dependent electrical and structural properties of BiFeO3 nanoparticles under electron irradiation

The paper deals with the effect of electron irradiation on the structural and electrical properties of BiFeO3 nanoparticles synthesized by standard sol-gel method. The samples were subjected to electron irradiation using a Microtron accelerator. The effects of irradiation on structural morphology viz grain size, microstrain and dislocation have been studied by X-ray diffraction (XRD). The current density of the samples at various doses of high energy electrons was also studied. It was observed that electrical conductivity depends on electron dose.

Variation of carrier concentration and interface trap density in 8MeV electron irradiated c-Si solar cells

The capacitance and conductance measurements were carried out for c-Si solar cells, irradiated with 8 MeV electrons with doses ranging from 5kGy – 100kGy in order to investigate the anomalous degradation of the cells in the radiation harsh environments. Capacitance – Voltage measurements indicate that there is a slight reduction in the carrier concentration upon electron irradiation due to the creation of radiation induced defects. The conductance measurement results reveal that the interface state densities and the trap time constant increases with electron dose due to displacement damages in c-Si solar cells.