Optical Beam Induced Current Imaging In Scanning Optical Microscopy

The use of scanning optical microscopy in the inspection and examination of electronic devices will be considered. In particular we will model the imaging of dislocations and defects present within a semiconductor via their influence on the reduction of the short circuit photocurrent as the laser beam of a scanning optical microscope scans over the device surface. The effects of parameters such as probe beam size, surface recombination velocity and minority carrier diffusion length will all be included. The predictions of the model will be compared with practically obtained results. We will also consider the various methods of measuring material parameters by optical beam scanning. Particular attention will be given to Schottky barrier devices from which the uncertainty in knowledge of surface recombinaton is removed. Analytical expressions will be presented for comparison with experimental data.