Microstructure of GaN_1-xBi_x

In this paper we describe detailed transmission electron microscopy studies of GaN_1-xBi_x with 0.05 < x <0.18 grown by low-temperature molecular beam epitaxy under Ga-rich conditions. Microstructural transformation from columnar growth separated by thin amorphous areas in the films with lowest Bi content (5%) to pseudo-amorphous structure with crystalline grains embedded in the amorphous matrix in the samples with higher Bi content (13% to 18%) was observed. In addition, metallic Bi segregation occurred in the samples with the highest Bi concentration. An abrupt decrease in absorption edge energy is found in samples with higher Bi content. © 2012 TMS (outside the USA).