Over the last few years, transition metal oxide layers have been proposed as selective contacts both for electrons and holes and successfully applied to silicon solar cells. However, better published results need the use of both a thin and high quality intrinsic amorphous Si layer and TCO (Transparent Conductive Oxide) films. In this work, we explore the use of vanadium suboxide (V2Ox) capped with a thin Ni layer as a hole transport layer trying to avoid both the intrinsic amorphous silicon layer and the TCO contact layer. Obtained figures of merit for Ni/V2Ox/c-Si(n) test samples are saturation current densities of 175 fA cm-2 and specific contact resistance below 115 mO cm2 on 40 nm thick V2Ox layers. Finally, the Ni/V2Ox stack is used with an interdigitated back-contacted c-Si(n) solar cell architecture fully fabricated at low temperatures. An open circuit voltage, a short circuit current and a fill factor of 656 mV, 40.7 mA cm-2 and 74.0% are achieved, respectively, leading to a power conversion efficiency of 19.7%. These results confirm the high potential of Ni/V2Ox stacks as hole-selective contacts on crystalline silicon photovoltaics.Peer ReviewedPostprint (published version

Mechanisms of (NH4)2Sx-treated III-V compound triple-junction solar cells incorporating with hybrid electrode Appl. Phys. Lett. 101, 033902 (2012) High-quality surface passivation of silicon using native oxide and silicon nitride layers Appl. Phys. Lett. 101, 021601 (2012) Crystalline silicon surface passivation by intrinsic silicon thin films deposited by low-frequency inductively coupled plasma J. Appl. Phys. 112, 013708 (2012) Imaging ambipolar diffusion of photocarriers in GaAs thin films J. Appl. Phys. 111, 123720 (2012) Low resistance Ti Ohmic contacts to 4H-SiC by reducing barrier heights without high temperature annealing

In this work we study the optimization of laser-fired contact (LFC) processing parameters, namely laser power and number of pulses, based on the electrical resistance measurement of an aluminum single LFC point. LFC process has been made through four passivation layers that are typically used in c-Si and mc-Si solar cell fabrication: thermally grown silicon oxide (Si0 2 ), deposited phosphorus-doped amorphous silicon carbide (a-SiC/H(«)), aluminum oxide (A1 2 0 3 ) and silicon nitride (SiN^/H) films. Values for the LFC resistance normalized by the laser spot area in the range of 0.65-3 mil cm 2 have been obtained.

A new Al2O3/TiO2/Mg electron-contact scheme together with a V2Ox-based hole-contact is applied to cold-IBC solar cells achieving efficiencies beyond 19%.

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Excellent passivation of n-type crystalline silicon surface is demonstrated by means of intrinsic amorphous silicon carbide (a-SiCx:H) thin films. An optimum CH4/SiH4 ratio is determined, leading to an effective surface recombination velocity, Seff, lower than 54 cm s−1. By adding a constant flow of N2 to the precursor gases, the surface passivation is improved to Seff⩽16 cm s−1. From infrared spectroscopy measurements of these films, it can be deduced that the N2 flow increases the carbon content of the layers for a constant CH4/SiH4 ratio. The dependence of the effective lifetime, τeff, on the excess charge carrier density, Δn, is measured using the quasisteady-state photoconductance technique, and these curves are simulated through an electrical model based on an insulator/semiconductor structure.

P1-type hydrogenated amorphous silicon–carbon (a-Si12xCx :H) on n-type crystalline silicon\ud (c-Si) heterojunction diodes were fabricated and characterized electrically. The effects of thermal\ud annealing on the electrical transport properties of a-Si0.8C0.2 :H/c-Si diodes were investigated by\ud measuring their current–voltage characteristics. From the dark current–voltage characteristics\ud measured at different temperatures (298–373 K), transport mechanisms were analyzed in detail.\ud Two carrier transport mechanisms were found to be the origin of forward current. At low bias\ud voltage and temperatures above 320 K as-deposited diodes are dominated by recombination currents\ud on the amorphous side of the space charge region whereas annealed diodes are mainly dominated by\ud diffusion mechanisms. In contrast, at temperatures below 320 K, both types of diodes are mainly\ud dominated by multitunneling capture emission. At higher voltages, the current becomes space\ud charge limited for both diodes throughout the temperature range studied.Peer Reviewe

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