Thermal analysis of GaN-based laser diode package

This paper reports on the thermal behavior of GaN-based laser diode (LD) package as functions of cooling systems, die attaching materials, and chip loading conditions. Thermal resistance and junction temperature was determined by electrical-thermal transient method. Significant change of thermal resistance with input current was observed under natural cooling condition due to the sensitive change of heat transfer coefficient (A) with temperature. Employment of PbSn as a die attachment was more advantageous over Ag-paste in thermal behavior of LD package. Compare the thermal resistance of LD packages epidown and epi-up structures. The partial thermal resistance from junction to submount is 4.68 K/W for epidown structure, and 9.65 K/W to epi-up structure. The results demonstrate that the total thermal resistance of LD package be controlled mainly by the packaging design rather than the chip structure itself.