Molecular beam epitaxy of GaN_1–<i>x</i>Bi_<i>x</i> alloys with high bismuth content

Abstract We have analysed bismuth incorporation into GaN layers using plasma‐assisted molecular beam epitaxy (PA‐MBE) at extremely low growth temperatures of less than ∼100 °C under both Ga‐rich and N‐rich growth conditions. The formation of amorphous GaN 1− x Bi x alloys is promoted by growth under Ga‐rich conditions. The amorphous matrix has a short‐range order resembling random crystalline GaN 1− x Bi x alloys. We have observed the formation of small crystalline clusters embedded into amorphous GaN 1− x Bi x alloys. Despite the fact that the films are pseudo‐amorphous we observe a well defined optical absorption edges that rapidly shift to very low energy of ∼1 eV.