Absorption spectra of bulk aluminum nitride crystals doped with Er³⁺ ions

Abstract

This Letter presents results of analysis of the absorption spectra of AlN:Er³⁺ bulk crystals. In the spectral of 370–700 nm, absorption lines responsible for intraconfiguration electron transition from the ground state ⁴I_15/2 to the excited states of Er³⁺ ions are found. Transitions to the levels of the ⁴F_9/2, ²H_11/2, and ⁴G_11/2 states at 2 K are studied in detail. The number of observed lines for these transitions fully agrees with that theoretically possible for f–f electron transitions in Er³⁺ 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, Er³⁺ occupies the position of Al. Energy positions of excited states for the considered transitions are determined.