INJECTION-LEVEL-DEPENDENT RECOMBINATION VELOCITIES AT THE SI-SIO2 INTERFACE FOR VARIOUS DOPANT CONCENTRATIONS

Measurements of the dependence of the effective surface recombination velocity S-eff at the Si-SiO2 interface on light-induced carrier concentration are presented. Contactless lifetime measurements by modulated free-carrier IR absorption with additional bias light and by photoconductance decay measurements of samples immersed in HF were used to extract S-eff for varying illumination levels. For various dopant concentrations the measured surface recombination velocities are compared with theoretical predictions calculated using an extended Shockley-Read-Hall formalism for Si-SiO2 interfaces. Good agreement was obtained. The consequences for solar cell performance and lifetime measurement techniques are discussed.