PROJECT TITLE :
Thermal modelling of transfer-bonded thin-film gallium arsenide laser diode
ABSTRACT:
Two-dimensional temperature distributions of skinny-film edge-emitting gallium arsenide (GaAs) three μm wide ridge lasers transfer-bonded to substrates with totally different thermal conductivities, k, were simulated in COMSOL. The thermal resistance, Rth, is compared with a simplified steady-state analytic expression. The effects of laser cavity length, thickness of dielectric passivation layer, contact metal layer thickness and submount material are investigated so as to cut back the thermal resistance of the laser when referenced to lasers with the native GaAs substrate. The simulations show the importance in reducing the GaAs substrate thickness particularly for short cavity lengths. The Rth of a 200 μm long laser with the substrate totally removed is 37.five K/W, compared with 230 K/W for the laser with a one hundred μm thick GaAs substrate. Increased p-contact metal thickness and reduced dielectric layer thickness any scale back Rth. If alumina (k = one.35 W/mK) is employed as a submount, its thickness higher than a perfect heat sink should be minimised to decrease the junction temperature. A ten μm thick silicon submount (k = 150 W/mK) on top of a excellent heat sink provides an acceptably low Rth.
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