Integrated electroplated heat spreaders for high power semiconductor lasers

Abstract

Thermal management of high power semiconductor lasers is challenging due to the low thermal conductivity of the laser substrate and the active device layers. In this work, we demonstrate the use of a microfabricated laser test device to study the thermal management of edge emitting semiconductor lasers. In this device, metallic heat spreaders of high thermal conductivity are directly electroplated on structures that mimic edge-emitting semiconductor lasers. The effects of various structural parameters of the heat spreader on the reduction of the thermal resistance of the laser test device are demonstrated both experimentally and theoretically. Without resolving to computational costive simulations, we developed two independent analytical models to verify the experimental data and further utilized them to identify the dominant thermal resistance under different laser mounting configurations. We believe our approach here of using microfabricated devices to mimic thermal characteristics of lasers as well as the developed analytical models for calculating the laser thermal resistance under different mounting configurations can potentially become valuable tools for thermal management of high power semiconductor lasers.

Continuous-wave operation of a 1.3 μm wavelength npn AlGaInAs/InP transistor laser up to 90 °C

“…Finally, a 3.5 μm thick Au layer was deposited by electrolytic plating (plating rate of 15 nm min −1 ) on the electrodes as a heat spreader. 28) Au plating pattern was formed using a lift-off process. Then, the wafer was made thinner (<200 μm) using lapping process.…”

Lasing characteristics of 1.3-µm npn-AlGaInAs transistor-laser with narrower-bandgap p-GaInAsP base layer on semi-insulating InP substrate

“…4-µm-thick Au layers were deposited on the electrodes of some of the devices by electrolytic plating to reduce thermal resistance. 29) The Au plating pattern was formed by a lift-off process. The plating current and deposition rate were 1 mA and 5 nm=min, respectively.…”

Thermal modelling of transfer‐bonded thin‐film gallium arsenide laser diode

“…It can provide actuate temperature distribution for the specific geometries. As the FEM simulation are time consuming for the large variation in critical dimensions in the laser structures, an analytical model based on the work of Fu et al [12] was also used to provide general guidelines for thermal management.…”

“…The analytical method of Joyce et al [11] and Fu et al [12] is used where the heat dissipation in the laser diode can be represented as a thermal resistance circuit composed of individual thermal resistance components. The total thermal resistance is obtained by calculating the sum of parallel and series components.…”

“…For convenience, a dimensionless temperature distribution in rectangular coordinates ϕ i ( x , y ) where ϕ i = ( T i − T 0 )/ T 0 is expressed for each layer [11–13]. Perfect thermal interface boundary conditions with continuous temperature and normal heat flow are assumed [11, 12]. The laser diode is assumed mounted on a perfect heat sink, with the interface between the laser substrate and the heat sink maintained at the same temperature as the heat sink ( T 0 ).…”