Thermal Analysis of High-Power Flip-Chip-Bonded Photodiodes

The performance of high-power photodiodes flip-chip bonded on polycrystalline aluminum nitride (AlN), single-crystal AlN, and diamond submounts are compared. The thermal boundary conductance (inverse of the thermal boundary resistance) between submount/titanium interfaces was measured and found to be the primary impedance to heat dissipation. Thermal profiles of the flip-chip-bonded devices were simulated to project the power density at failure, which is found to be inversely proportional to the diameter of the photodiodes.