Correlating Semiconductor Laser Performance with Wafer Level Spatially Resolved Photoluminescence
01 January 2001
Photoluminescence (PL) mapping systems are used to evaluate wafer uniformity and quality during semiconductor laser processing. Metrics such as PL efficiency and threshold are determined by measuring PL intensity as a function of excitation level. PL mapping systems typically employ spot sizes in the hundred micron range. Maps are generated by stepping the excited spot over a wafer. Processing devices such as the electro-absorption modulated laser (EML) incorporate two aspects that disable common mapping systems - selective area growth, and mesa delineation. Selective area growth (SAG) deposits gain and modulator sections in close proximity, requiring a spatial resolution of about 10 microns. After mesa delineation, a spatial resolution of 1 micron is needed for evaluating waveguide uniformity.