Optoelectronic transport property measurements of an amorphous-silicon-passivated c-silicon wafer using non-contacting methodologies

Abstract

Photocarrier radiometry (PCR), microwave photoconductivity decay (μ-PCD) and transient and quasi-steady-state eddy currents were used for the characterization of a crystalline (c-) Si wafer passivated with intrinsic hydrogenated amorphous silicon films on either front or back side, or on both sides of the wafer. All three techniques are capable of measuring recombination lifetimes, however additional fundamental free photoexcited carrier transport parameters (diffusion coefficient, front- and back-surface recombination velocity) can be evaluated from the PCR frequency dependence owing to the free-carrier-density wave's diffusion-length depth-dependence on frequency. The measured recombination lifetimes are compared and differences in values among the three techniques are discussed in terms of the role of surface and interface defects. μ-PCD and eddy currents yield effective or vertically averaged lifetime measurements, as opposed to PCR which yields bulk recombination lifetimes separately from surface recombination effects.