Characterization and Diagnosis of Silicon Wafers, Ingots, and Solar Cells

Impact of Nanostructuring on the Photoelectrochemical Performance of Si/Ta3N5 Nanowire Photoanodes

“…To assess the effects of nanostructuring Si on the charge carrier properties and lifetimes, we measured the effective minority carrier lifetimes, τ eff , of the n-type Si cores using photoconductance decay measurements. τ eff encompasses several recombination mechanisms including the bulk processes (radiative, Auger, and Shockley–Read–Hall recombination) and surface recombination: , We performed these measurements in a quasi-steady-state configuration where the effective minority carrier lifetime is found as a function of excess carrier density, Δ n , under steady-state photogeneration, G : ,, Lifetime depends on carrier injection level; hence, we report it at a given minority carrier density, Δ p , where Δ p = Δ n because electron–hole pairs are photogenerated upon light illumination …”

“…As τ eff encompasses both surface and bulk lifetimes, in theory, a high-quality passivating layer such as a thermal silicon dioxide, silicon nitride, or alumina should passivate the surface states of Si well enough to yield a sufficiently low surface recombination velocity and therefore a quantifiable bulk lifetime . In our system, we employed a passivation layer in the form of Ta 2 O 5 by atomic layer deposition.…”

“…Carrier lifetime measurements were performed on a Sinton Instruments WCT-100 wafer lifetime measurement tool in quasi-steady-state photoconductance decay mode. , The wafer inductance was tuned for each wafer, and an optical constant of 0.74 was set to account for the reduced reflectance off of the Si nanostructures as calculated from PC1D simulations from a model provided by Sinton Instruments. Planar Si recombination lifetimes were measured with the standard optical constant of 0.7.…”