Thermal behavior of visible AlGaInP-GaInP ridge laser diodes

The thermal behavior of visible AlGaInP-GaInP ridge laser diodes was investigated numerically and experimentally. It is shown that various parameters critically influence the thermal resistance, R, of such devices. R is inversely proportional to the thermal conductivity of the heat sink. A substantial improvement in R is achieved for junction-side-down mounting compared to junction-side-up. R depends strongly on the width, w, of the ridge, and this effect is different for junction-side-up or junction-side-down mounting. In the first case, R approximately log(w) and in the second, R approximately 1/w. The thickness of the soldering material is a sensitive parameter which may increase the value of R by up to 15 K/W. For junction-side-up mounted devices, the top metallization layer has a very favorable effect: a 1- mu m-thick gold layer reduces R by 30%. It is shown that when a laser is switched on, the thermal steady state is reached in the millisecond time range. The experimental results show very good agreement with numerical data.>