Photoluminescence from Be-Doped GaN Grown by Metal-Organic Chemical Vapor Deposition

A systematic photoluminescence study of Be-doped GaN grown by metal-organic chemical vapor deposition is presented. All Be-doped samples show the ultraviolet luminescence (UVLBe) band with a maximum at 3.38 eV and the yellow luminescence (YLBe) band with a maximum at approximate to 2.15 eV in GaN:Be having various concentrations of Be. The UVLBe band is attributed to the shallow state of the Be-Ga acceptor with a delocalized hole. The YLBe band is caused by a Be-related defect, possibly the polaronic state of the Be-Ga acceptor with the charge transition level at 0.3 eV above the valence band. This broad band exhibits unusual properties. In particular, it always shows two steps in its thermal quenching. The second step at T approximate to 200 K is attributed to the emission of holes from the 0.3 eV level to the conduction band. The origin of the first step remains unexplained.

Automated summary

A systematic study of photoluminescence in Be-doped GaN grown by metal-organic chemical vapor deposition reveals the presence of ultraviolet and yellow luminescence bands, attributed to the shallow and polaronic states of the Be-Ga acceptor, respectively. The yellow luminescence band exhibits a unique two-step thermal quenching behavior.