New quantitative line scanning technique for homogeneity assessment of semi-insulating GaAs wafers

Abstract
A new technique for recording spatial fluctuations of the optical absorption in GaAs slices is reported. It is based on a commercially available linear silicon diode array which monitors the optical absorption attributed to the omnipresent deep trap named EL2. Because this technique gives quantitative results, displays excellent spatial resolution (200 μm for 2-in. wafers), and is fast, it appears to be highly useful for wafer characterization and quality control.