Origin and impact of crystallographic defects in epitaxially grown Si wafers
In recent years epitaxially grown wafers (EpiWafers) made their way from small laboratory to production scale fabrication. A lot of effort has been put into upscaling of tools, improvement of material quality and in the fabrication of highly efficient solar cells. In this publication we investigate typical crystal defects appearing in EpiWafer material and correlate them with process or reactor specific features like porous templates, thick epitaxial layer growth or inline processing. We find two categories of stacking faults (SFs) which are either decorated with inclusions or not. Besides particles on the surface of the growth template contaminations with oxygen are found to be reasons for such polycrystalline inclusions. Stress leads to either delamination of the template or local lattice strain both reasons for defect growth. Parallel faults which propagate along slipping lines in the material are interacting with SFs although the correlation is not fully understood yet. Finally the recombination activity in SFs is found to be especially high where the 111 planes meet or when strong decorating occurs. This work is a first step to systematically investigate the crystallographic nature of EpiWafer material and will help to further improve processes and equipment.