Measurement of mounting-induced strain and defects in high-power laser diodes using Fourier-transform photo-current spectroscopy

We use Fourier-transform (FT) photo-current (PC) spectroscopy for the investigation of strain and the appearance of defects in high-power laser diode arrays (LDA). We study thermally induced strain and defects caused by device packaging with help of this noninvasive technique. The lifetime of the LDA strongly depends on the temperature of the active layer. It is important to realize a very good heat removal away from the active region (Tummala and Rymaszewski, Microelectronics Packaging Handbook, New York, 1989; Jain et al., Semicond. Sci. Technol. 11 (1996) 641). Examining similar LDAs (‘cm-bars’) on various heat spreader materials we find tensile or compressive mounting-induced strain contributions. We correlate the laterally resolved input of stress with the appearance of defect bands observed in the spectra. We present a relation between stress and defect concentration.