Absorption spectra of bulk aluminum nitride crystals doped with Er ions

This Letter presents results of analysis of the absorption spectra of AlN:Er bulk crystals. In the spectral of 370–700 nm, absorption lines responsible for intraconfiguration electron transition from the ground state I to the excited states of Er ions are found. Transitions to the levels of the F, H, and G states at 2 K are studied in detail. The number of observed lines for these transitions fully agrees with that theoretically possible for – electron transitions in Er ions found in a noncubic crystal field. The small width of the observed lines and their number indicate that erbium ions displace mostly one regular crystal position. Most probably, Er occupies the position of Al. Energy positions of excited states for the considered transitions are determined.