Yellow luminescence gallium vacancies

In n-type GaN the lowest-energy native defect is the gallium vacancy (Vg ), a triple acceptor. This defect plays a role in donor compensation (see Datareview A8.1), as well as in the frequently observed yellow luminescence (see Datareview A8.7). 

At this time the gallium vacancy (in isolated form or complexed with an impurity) appears to be the most likely source of the yellow luminescence. In this Datareview we will summarise the available evidence. 

FIGURE 1 Schematic illustration of levels involved in the yellow luminescence in GaN. Gallium vacancies introduce a deep acceptor level about 1.1 eV above the valence band Transitions between shallow donors and the deep acceptor level give rise to the YL. 

Strong theoretical as well as experimental evidence is now available identifying gallium vacancies as the source of the yellow luminescence in GaN. 

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