Contactless Estimation of the Surface Recombination Velocity at High-Low Junction Surfaces Fabricated by the Ion-Implantation Technique

Abstract

Surface properties of ion-implanted silicon are investigated by the microwave photoconductivity decay method. The effective surface recombination velocity (S) is estimated by fitting of the experimental decay curve of excess carrier concentration with a theoretical decay curve. The results show that S is almost inversely proportional to the carrier concentration of the heavily doped layer formed by the ion-implantation for both types of high-low junction ( n+n, p+p). Thus the present method is a powerful tool for surface characterization.

Field Passivation of the Silicon Wafer Rear Surface for Reliable Bulk Recombination Lifetime Measurement

“…4a͒. [24][25][26] Due to the high acceptor concentration close to the back-side surface, the barrier becomes virtually independent on the oxide charge, and stable contamination monitoring with high sensitivity to bulk impurities becomes possible even in the case of varying oxide and interface charges.…”

“…[19][20][21] For high-efficiency solar cells it was recognized that such a field passivation may be accomplished by an external voltage, 20,22 by corona charge on an insulation layer, 23 or by an appropriate doping profile close to the surface, which sets up a potential barrier for minority carriers. [24][25][26] In recombination lifetime techniques employing conductive contacts to the semiconductor structure under investigation, 27 the sur-z E-mail: matthias.boehringer@de.bosch.com face potential and thus the surface recombination rate can be controlled externally. For noncontact methods the surface potential is a priori determined by internal parameters, such as oxide charge, interface trapped charge, and substrate doping.…”