The former consists of: a 20 nm-thick low temperature GaN buffer layer; 2 μm-thick unintentionally doped GaN; 500 nm-thick silicon-doped GaN; 1.5 μmthick silicon-doped AlGaN; 30 nm-thick n-GaN; a supperlattice active layer, formed from ten pairs of GaN and Ga0.79In0.21N, both 3 nm-thick, followed by a final barrier of GaN; 20 nm-thick Mg-doped p-AlGaN; 50 nm-thick p-GaN; and 10 nm-thick p+ GaN.


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This article has a picture of the layers and the molecular make up of each. Very informative.