Indium gallium nitride

Indium gallium nitride (InGaN, In_xGa_1−xN) is a semiconductor material made of a mix of gallium nitride (GaN) and indium nitride (InN). It is a ternary group III/group V direct bandgap semiconductor. Its bandgap can be tuned by varying the amount of indium in the alloy. In_xGa_1−xN has a direct bandgap span from the infrared (0.69 eV) for InN to the ultraviolet (3.4 eV) of GaN. The ratio of In/Ga is usually between 0.02/0.98 and 0.3/0.7.

Indium gallium nitride is the light-emitting layer in modern blue and green LEDs and often grown on a GaN buffer on a transparent substrate as, e.g. sapphire or silicon carbide. It has a high heat capacity and its sensitivity to ionizing radiation is low (like other group III nitrides), making it also a potentially suitable material for solar photovoltaic devices, specifically for arrays for satellites.

It is theoretically predicted that spinodal decomposition of indium nitride should occur for compositions between 15% and 85%, leading to In-rich and Ga-rich InGaN regions or clusters. However, only a weak phase segregation has been observed in experimental local structure studies. Other experimental results using cathodoluminescence and photoluminescence excitation on low In-content InGaN multi-quantum wells have demonstrated that providing correct material parameters of the InGaN/GaN alloys, theoretical approaches for AlGaN/GaN systems also applies to InGaN nanostructures.

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