Infrared imaging of semiconductor lasers

The implementation of infrared imaging for the purpose of thermal analysis of semiconductor lasers is demonstrated. The experimental results obtained in the different spectral bands ranging from near IR (1.5-2 mu m) to mid IR (8-13 mu m) are presented. The results show the applicability of the method for steady-and transient-state characterization of individual as well as multi-emitter laser structures. Moreover, various aspects of the defect detection are discussed. We demonstrate the detection of defects that are not only located at the front facet of the laser, but also deeper in the cavity. The effects of radiative recombination at defect centres are distinguished from purely thermal effects by transient analysis of infrared images. It is shown that the near IR band (1.5-2 mu m) deep-level luminescence is responsible for these effects. This finding is independently proved by complementary measurements of the near IR emission spectrum as well as by characterization of absorption properties of the devices in the below-band edge region. The information from two distinct spectral channels of an infrared imaging system (near IR and mid IR) is used for pre-selection of potentially long-lived devices. It is shown that conventional burn-in tests do not discard all devices which have a limited lifetime. Thus, infrared imaging is considered a potential industrial screening tool with measuring times of fractions of a second only.