Correlation between structural defects and carrier lifetime

In 4H SiC substrate and epitaxial films, due to the influence of epitaxial process and growth conditions, there are many structural defects in the SiC epitaxial layer, such as thread dislocation TSD, thread edge dislocation TEDS, base plane dislocation BPDS, microtubule super TSD, 10 °low angle grain boundary, endogenous stacking faults, carrot shaped morphological defects, etc. These defects will affect the performance of the device more or less.

Of course, the characterization means of many defects are gradually improved. In order to eliminate the influence of defects, it is necessary to understand these means. First and foremost, time resolved photoluminescence (TRPL) is a very effective means to measure the radiative recombination between excitons and donors, and cathodoluminescence is also a good means to characterize the lifetime.

By providing electron beams to samples, the lifetime distribution can be well obtained. Other methods can provide a good relationship between the needle sample and the life. In addition, the comparison between the defects and the life diagram can well show that these structural defects do have a certain impact on the effective life of local carriers.

Further reading: J. Bergman,O. Kordina,E. Janzén,“Time Resolved Spectroscopy of Defects in SiC”,in,phys.stat.sol.(a)162,65(1997) Serguei I.Maximenko,Jaime A. Freitas Jr.,Paul B. Klein,Amitesh Shrivastava,and TangaliS. Sudarshan, “Cathodoluminescence study of the properties of stacking faults in 4H-SiC homoepitaxial layers”,in,Appl.Phys.Lett.94,092101(2009) J.Hassana and J.P.Bergman,“Influence of structural defects on carrier lifetime in 4H-SiC epitaxial layers:Optical lifetime mapping”,in,Journal of Applied Physics 105,123518(2009) Nadeemullah A. Mahadik, Robert E.Stahlbush, Joshua D. Caldwell,Michael O’Loughlin, and Albert Burk, “Correlation of Extended Defects on Carrier Lifetime in Thick SiC Epilayers”,in,Materials Science Forum Vols.717-720(2012)pp297-300