Grain orientation of Y₂O₃–Si₃N₄ thin-film on the power-handling of InGaAs/AlAsSb ultrafast all-optical cross-phase modulators

Grain orientation is known to yield high thermal conductivity oriented yttrium silicon oxynitride (Y₂O₃–Si₃N₄). However, the anisotropic thermal conductivity of oriented Y₂O₃–Si₃N₄ in the stacking direction falls below that of nonoriented Y₂O₃–Si₃N₄ and Si₃N₄ at temperatures above 280 K and 630 K, respectively. Hence, it is unclear will grain orientation actually lead to better heat diffusions from the InGaAs/AlAsSb ultrafast all-optical cross-phase modulators or any other semiconductor devices to the oriented Y₂O₃–Si₃N₄ thin-film. To probe into this, the heat diffusion in an InGaAs/AlAsSb ultrafast all-optical cross-phase modulator whereby nonoriented and oriented Y₂O₃–Si₃N₄ thin-films are used as the heat-spreader is performed. Analysis shows that grain orientation in Y₂O₃–Si₃N₄ thin-film reduces the thermal resistance at the device-film interface through reduced void density, and leads to a marginally better heat diffusion in the device compared to nonoriented Y₂O₃–Si₃N₄ thin-film. Consequently- - , oriented Y₂O₃–Si₃N₄ thin-film heat-spreader improves the power-handling of the InGaAs/AlAsSb ultrafast all-optical cross-phase modulator by ∼0.46–∼1.8 times of the original value compared to ∼0.36–∼1.75 times of the original value for the case of nonoriented Y₂O₃–Si₃N₄ thin-film heat-spreader.