Imaging IR System for NDE of GaAs Wafers

The performance of lasers, solar cells, and other devices fabricated from doped GaAs wafers depends strongly on the quality of the underlying wafer. For best performance, the wafers must have uniform carrier concentration and low defect density. GaAs wafer manufacturers and users currently do not have a rapid, non-destructive way of measuring these parameters. As a result, GaAs devices remain expensive due to relatively low device yields. We propose to develop a system to measure these properties by measuring the wafer transmissibility at selected wavelengths in the IR. The proposed imaging IR system will allow rapid, accurate, high-resolution and inexpensive measurement of wafer electrical properties. In Phase I, Creare will prove the feasibility of the method by developing proof-of-concept hardware and software and comparing the NDE measurements with results from conventional destructive techniques. In Phase II, we will automate the system and make it clean-room compatible.