Graphic script provides quick classification of GaAs wafers

AbstractInfrared transmission topography has long been used to detect variations in gallium arsenide wafers that can cause dark-line defects that limit lifetime of GaAs lasers and solar cells. In the past, infrared transmission was measured over a whole wafer by scanning a small spot mechanically. Absorption was calculated at each location across the surface of the wafer and used to produce colour-coded plots that allow the wafer's characteristics to be determined at a glance. The program ran on VAX/VMS computers, but these are being taken out of service due to obsolescence. To overcome these problems, the author developed a graphics script using a state-of-the-art data analysis program which provides quick classification of GaAs wafers based on traps and defects, but runs on inexpensive personal computers and, as a bonus, produces bit-map plots that can be cut and pasted into Windows word processing and presentation software