Bulk and Surface‐Related Degradation in Lifetime Samples Made of Czochralski Silicon Passivated by Plasma‐Enhanced Chemical Vapor Deposited Layer Stacks

• Published in: Physica status solidi. A, Applications and materials science Vol. 215; no. 24
• Main Authors: Sperber, David, Schwarz, Anton, Herguth, Axel, Hahn, Giso
• Format: Journal Article
• Language: English
• Published: Weinheim Wiley Subscription Services, Inc 01.12.2018
• Subjects: Carrier lifetime; Charge density; Chemical vapor deposition; Current carriers; Czochralski; Degradation; High temperature; LeTID; Light; light‐induced degradation; Organic chemistry; PECVD; Silicon; Stacks; surface‐related degradation
• ISSN: 1862-6300; 1862-6319
• DOI: 10.1002/pssa.201800741

Significant bulk‐related degradation (BRD) is followed by surface‐related degradation (SRD) of effective excess charge carrier lifetime in lifetime samples made of Czochralski silicon during illuminated treatment at 80–150 °C. Samples are passivated with either AlOx:H/SiOxNy:H/SiNx:H or SiOxNy:H/SiNx:H stacks stemming entirely from plasma‐enhanced chemical vapor deposition. Samples show strong variations in BRD depending on passivation stacks and treatment conditions, and a potential link to light and elevated temperature‐induced degradation (LeTID) is discussed. All samples are fired in a belt furnace, and variations of firing temperature and belt speed are shown to influence SRD slightly. SRD is furthermore accelerated with increasing treatment temperature and an apparent activation energy Eapp = 1.07 ± 0.02 eV is determined in SiOxNy:H/SiNx:H passivated samples. Interpretation of Eapp is, however, difficult as both changes in interfacial defect and fixed charge density occur in parallel during SRD. Cz‐Si lifetime samples coated with different PECVD passivation layer stacks are found to suffer from severe bulk and surface‐related degradation during illuminated treatment at elevated temperatures. Significant degradation can already be observed at 80 °C and 1 sun equivalent illumination. Degradation properties and an apparent activation energy of surface‐related degradation are discussed in detail.