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The influence of the Si-H2 bond on light-induced degradation and the thermal recovery of a-Si films and a-Si solar cells were studied. The influence of the Si-H2 bond on light-induced degradation depends on the impurity content in a-Si films, and light-induced degradation can be reduced by decreasing the Si-H2 bond density in a-Si films with impurity content of 1018 cm-3. The activation energy of the thermal recovery process was about 1.0 eV, and it did not depend on the Si-H2 bond density. However, an irreversible phenomenon was observed in film properties and solar cell characteristics with high Si-H2 bond density. It is thought that the structural flexibility of the Si-H2 bond is related to this irreversible phenomenon.

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We have demonstrated interface-treated Josephson junctions without deposited barriers in a trilayer structure. In the junctions, barriers were formed through an etching process and an annealing process for base YBa2Cu3O7-x (YBCO) films. The junctions showed resistively-shunted-junction-type characteristics over the entire temperature range below 70 K. A magnetic field modulation of more than 80% was observed throughout the operating temperature range. The obtained I c R n product was 2.1 mV at 4.2 K. The 1σ spreads in the junction parameters of 10% or better were observed for eight out of nine junctions in a chip.

We have studied the influence of process parameters on electrical properties for interface-modified junctions (IMJs) based on YBa2Cu3Ox. Tunnel barriers are produced by an electron cyclotron resonance (ECR) plasma etching process and subsequent vacuum annealing. We have found that time and accelerating voltage (V acc) in the etching sequence, in which the ramp-edge geometry is defined, are very important parameters for the barrier formation. Increasing the etching time and accelerating voltage lead to the reduction of critical current densities. By setting these parameters at appropriate values, we can control the critical current of the IMJs. We have also found that the IMJs with high junction resistance, which are fabricated at higher accelerating voltages above 700 V, have transport mechanisms via localized states for quasi particles. The X-ray photo spectroscopy analysis suggests that accelerating voltages above 700 V enhance the thickness of the barrier, while those below 700 V affect both barrier resistivity and thickness.

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