Local Heat Energy Transport Analyses in Gallium-Indium-Nitride/Gallium Nitride Heterostructure by Microscopic Raman Imaging Exploiting Simultaneous Irradiation of Two Laser Beams

Local heat transport in two Ga_xIn_1-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 Ga_0.84In_0.16N 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 Ga_0.84In_0.16N layer to the GaN under layer is blocked in the high-density area of misfit dislocation in the vicinity of the heterointerface.