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This work reports upon the dilution effect of Ar + H2 on the microstructures, optical, and photovoltaic properties of the hydrogenated nanocrystalline silicon (nc-Si:H) thin films. High crystallinity (up to 82.6%) nc-Si:H thin films were fabricated from silane diluted by Ar + H2 in a low-frequency inductively coupled plasma (LFICP) facility at a low temperature of 300 °C. The substitution of H2 by Ar in the diluent gas leads to an increase of the deposition rate, grain size, and crystallinity, and a decrease of the optical bandgap. Varying the Ar content caused a fluctuation of the H concentration and a change of the preferential orientation from (111) to (220) in the synthesized thin films. These effects physically originated from changes of the Ar + H2 + SiH4 plasma environment in the LFICP system. The enhancement of the dissociation of SiH4/H2 molecules by ion Ar+ and the metastable state Ar* were discussed in terms of related chemical reactions between the diluent gases and silane. Furthermore, it was found that a heterojunction solar cell prototype based on the as-deposited nc-Si:H thin films exhibits an excellent photovoltaic response. [ABSTRACT FROM AUTHOR]

Though separate studies on the individual properties of photovoltage and magnetoresistance (MR) have made much progress, work integrating the two phenomena into one kind of structure has not been reported so far. This study combines MR and lateral photovoltage (LPV) in a magnetic oxidized film Co3Mn2O deposited on an n-type Si substrate with a native ultrathin SiO2 surface by sputtering. The effective resistance shows a marked transition for temperature around 240 K. Both negative MR {MR = [R(H)- R(0)]/R(0)×100%} of -11% at 4.2K and a large positive MR of 70% at 300K at a magnetic field of 6 T were observed. This phenomenon can be explained by the conducting channel switching from the upper film to the Si inversion layer. Under the nonuniform illumination of a laser beam, the LPV shows a high sensitivity to the spot position on the Co3Mn2O film plane. The current-voltage (I -V) characteristic of the Co3Mn2O/SiO2/Si metal-oxide-semiconductor (MOS) structure exhibits rectifying I-V behavior, which suggests that the lateral photoeffect (LPE) can be interpreted in terms of the metal-semiconductor (MS) junction that exists between the magnetic film and silicon substrate. When an external magnetic field is applied perpendicular to the film, the LPV shows a monotonic increase with increasing magnetic field. The variation of LPV reaches 93.2% at 2 T. This intriguing effect may be due to the Lorentz force acting on the photo-generated carriers. [ABSTRACT FROM AUTHOR]

Hydrogenated silicon suboxide (SiOx : H) thin films are fabricated by a low-frequency inductively coupled plasma of hydrogen-diluted SiH4 + CO2 at a low temperature (100 °C). Introduction of a small amount of oxygen into the film results in a predominantly amorphous structure, wider optical bandgap, increased H content, lower conductivity and higher activation energy. The minority carrier lifetime in the SiOx : H-passivated p-type Si substrate is up to 428 µs with a reduced incubation layer at the interface. The associated surface recombination velocity is as low as 70 cm s−1. The passivation behaviour dominantly originates from the H-related chemical passivation. The passivation effect is also demonstrated by the excellent photovoltaic performance of the heterojunction solar cell with the SiOx : H-based passivation and emitter layers. [ABSTRACT FROM AUTHOR]