Studies of GaAs:Er impact excited electroluminescence devices

We report on the study of impact excitation of Er ions in GaAs. The metalorganic chemical vapor deposition grown, p⁺-n structured electroluminescence (EL) devices were fabricated by growing, at different temperatures, GaAs:Er layers on top of the n⁺ GaAs substrates. P ⁺ layers of GaAs were made by Zn diffusion from the top surfaces. When we forward biased these diodes, the EL spectra were similar to the respective photoluminescence (PL) spectra of each sample. The spectra of the samples differed for the various growth temperatures. However, when we reverse biased these diodes, the EL spectra are the same for all samples but different from the PL spectra. These results indicate that the Er center(s) excited by direct impact is different from the Er center(s) excited through electron-hold recombination and the subsequent energy transfer.