Response Time Measurements and Flying Spot Technique in Microcrystalline Silicon Solar Cells

Abstract

ABSTRACTTransverse charge collection in a p-i-n structure based on microcrystalline silicon and lateral transport in a single intrinsic layer were analyzed using transient photoconductivity (TPC), steady-state photocarrier grating analysis (SSPG), and the flying spot technique (FST). Photocurrents were excited either with HeNe laser light (633 nm, intensity about 20 mW/cm2) or with 5 ns pulses from a Nd:YAG laser (532 nm, peak power of about 500 kW/cm2 with 5 mJ pulses). The response time τR varied greatly from about 3 ms at low intensity down to a few μs under pulsed laser excitation. The minority carrier diffusion length LD measured by FST in diode structures was usually larger than values obtained from the SSPG method applied to intrinsic microcrystalline layers.