TY - JOUR

T1 - Two-stage permanent deactivation of the boron-oxygen-related recombination center in crystalline silicon

AU - Steckenreiter, Verena

AU - Walter, Dominic C.

AU - Schmidt, Jan

N1 - Funding Information: The authors thank Cornelia Marquardt for sample proces sing and Nadine Wehmeier and Dennis Bredemeier for fruitful discussions. This work was funded by the Geram n State of Lower Saox ny and the Geram n Federal iM nistry of Econoim cs and Energy (WiMB ) iw th in the research project “Upgrade iS -PV” under contract oN . 0325877.B

PY - 2017/10

Y1 - 2017/10

N2 - We analyze the lifetime evolution during permanent deactivation of the boron-oxygen-related defect center (BO defect) in boron-doped, oxygen-rich Czochralski-grown silicon (Cz-Si). In particular, we examine the impact of the samples' states prior to the permanent deactivation process. Samples that were initially fully degraded show a two-stage deactivation process consisting of a fast and a slow deactivation component, which can be fitted by two exponential functions with their respective rate constants. For both components, we find a pronounced increase of the rate constants with illumination intensity. In addition, we observe that the rate constant describing the slow deactivation component of samples deactivated after complete degradation is identical to the rate constant determined on samples, which were deactivated immediately after annealing in darkness. In the latter case, a purely mono-exponential deactivation behavior was observed. Our study clearly demonstrates that the asymptotic deactivation behavior does not depend on the initial state of the lifetime sample. We prove that the same is valid for initially degraded and dark-annealed PERC solar cells. Hence, it is not necessary to first degrade the sample to realize a fast BO deactivation.

AB - We analyze the lifetime evolution during permanent deactivation of the boron-oxygen-related defect center (BO defect) in boron-doped, oxygen-rich Czochralski-grown silicon (Cz-Si). In particular, we examine the impact of the samples' states prior to the permanent deactivation process. Samples that were initially fully degraded show a two-stage deactivation process consisting of a fast and a slow deactivation component, which can be fitted by two exponential functions with their respective rate constants. For both components, we find a pronounced increase of the rate constants with illumination intensity. In addition, we observe that the rate constant describing the slow deactivation component of samples deactivated after complete degradation is identical to the rate constant determined on samples, which were deactivated immediately after annealing in darkness. In the latter case, a purely mono-exponential deactivation behavior was observed. Our study clearly demonstrates that the asymptotic deactivation behavior does not depend on the initial state of the lifetime sample. We prove that the same is valid for initially degraded and dark-annealed PERC solar cells. Hence, it is not necessary to first degrade the sample to realize a fast BO deactivation.

KW - Czochralski silicon

KW - boron-oxygen defect

KW - carrier lifetime

KW - permanent deactivation

UR - http://www.scopus.com/inward/record.url?scp=85031946639&partnerID=8YFLogxK

U2 - 10.1016/j.egypro.2017.09.350

DO - 10.1016/j.egypro.2017.09.350

M3 - Conference article

VL - 124

SP - 799

EP - 805

JO - Energy Procedia

JF - Energy Procedia

SN - 1876-6102

ER -