Anisotropic heat transport in a Ga 0.84 In 0.16 N/GaN-heterostructure on a sapphire substrate is observed from microscopic Raman images obtained by utilizing coaxial irradiation of two laser beams, one for heating (325 nm) in the GaInN layer and the other for signal probing (325 nm or 532 nm). The increase in temperatures of the GaInN layer and the underlying GaN layer is probed by the 325-nm and 532-nm lasers, respectively, by analyzing the shift in the Raman peak energy of the higher energy branch of E 2 modes. The result reveals that energy diffuses across a considerable length in the GaInN layer, whereas the energy transport in the perpendicular direction to the GaN layer is blocked in the vicinity of misfit dislocations on the heterointerface. This simultaneous irradiation of two lasers for heat generation and probing is effective in the microscopic analysis of energy transport through heterointerfaces.

Local heat transport in two GaxIn1-xN/GaN-heterostructures on sapphire substrates is investigated by microscopic Raman imaging using two lasers of 532 nm (Raman observation) and 325 nm (heat generation and Raman observation), which enables the separation of heat generation and Raman observation positions. It is found that E2(high) and A1(LO) modes of the Ga0.84In0.16N layer exhibit mutually different characteristics, which indicates the analysis of the occupation of the A1(LO) mode is available. E2(high) mode of the GaN layer observed by the 532-nm laser reveals that the transport of the heat energy generated in the Ga0.84In0.16N layer to the GaN under layer is blocked in the high-density area of misfit dislocation in the vicinity of the heterointerface.

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