Is n-type multicrystalline silicon the best candidate for short-term high-efficiency lower-cost solar cells?

Abstract

. In this article we detail a theoretical and

experimental investigation in order to reveal the advantageous

properties of multicrystalline n-type silicon for lower-cost high

quality solar cells applications. In this study, electronic grade

(EG) and compensated upgraded metallurgical grade (UMG)

materials are analyzed.

Three microwave-based contactless techniques (Microwave

Photoconductivity Decay “µw-PCD”, Microwave Phase-Shift

“µw-PS” and Large-Scale Microwave Phase-Shift “LS-µw-PS”)

are applied to determine the carrier lifetime behaviour in an

entire EG silicon ingot. We show that, at low injection

conditions, the minority carrier lifetime profile is not directly

related to resistivity variation along the ingot height. The carrier

lifetime variation observed in all three techniques is related to

Shockley-Read-Hall recombination process.

In compensated UMG silicon a higher minority carrier lifetime

is observed in n-type than p-type area at the same conditions of

contamination and injection level.