LIFETIME MEASURED BY LOW INJECTION LEVEL μ-PCD TECHNIQUE

摘要

The non-contact, non-destructive microwave photoconductivity decay (μ-PCD) technique is well established for the determination of effective carrier lifetimes in silicon material and a useful tool in monitoring different production steps. The measured lifetime is influenced by bulk and surface effects, whereby the bulk lifetime is a characteristic parameter of the material. We show that the Corona charge method in combination with μ-PCD gives an excellent, easy to use technique to suppress the surface effects and to determine bulk lifetime on oxidized samples. Using Corona charging it is possible to reduce the effective surface recombination velocity down to the 1 cm/s region. Furthermore the influences of injection level in conjunction with bias light on the measured lifetimes will be presented. This point is very important in the interpretation and comparison of effective lifetime measurements for defect and impurity identification.