FRACTURE PHENOMENA IN SILICON IMAGED BY INFRARED RADIATION FROM EJECTED SMALL PARTICLES

We have found that fracture of silicon wafer specimens without introdu ced flaws takes place with the ejection of many small particles that e mit infrared radiation, which has been imaged With a sensitive CCD cam era. The particles are of order micron dimensions, preventing surface- barrier separation of carriers excited by the bond breaking at cleavag e. Furthermore, larger ejected particles can subsequently crack, allow ing further ejection of small luminescent particles. The results show that a simple theory of spread of a pre-existing flaw can be a serious oversimplification of complex phenomena occurring at the onset of bri ttle cleavage. (C) 1998 American Institute of Physics.