Spatially resolved crack-tip stress analysis in semiconductor by cathodoluminescence piezospectroscopy.

A spatially resolved cathodoluminescence piezospectroscopic analysis is attempted for the high-resolution evaluation of the stress field developed ahead of the tip of an equilibrium crack propagating in a semiconductor. GaN was selected for this assessment as a paradigm semiconductor material. Quantitative measurements of in-plane luminescence probe response function (PRF) were preliminarily performed at different acceleration voltages upon scanning across a straight and atomically sharp interface between GaN and gold metal. Then, based on the knowledge of PRF, the convoluting effect due to the finite size of the electron probe could be corrected and an improved plot of the crack-tip stress field could be retrieved by a computer-aided data restoration procedure. The crack-tip stress intensity factor KI obtained by the cathodoluminescence piezospectroscopic method was compared with that obtained on the same crack path according to high-resolution measurements of crack-tip opening displacement. This study not only shows that a nanometer-scale spatial resolution can be experimentally achieved in a stress analysis of semiconductor materials but also that a stress data treatment based on experimental PRF is a viable approach to greatly reduce the error involved with the finite size of the electron probe. [ABSTRACT FROM AUTHOR]