Photoluminescence Excitation Measurements on Erbium Implanted GaN

摘要

The temperature dependence of the optical excitation cross section of Er implanted n-type GaN was studied using photoluminescence excitation spectroscopy. Due to the large 3.4 eV band gap of GaN, it was possible to probe two Er absorption lines using a tunable Ti:sapphire laser in the 770-1010 nm range. Photoluminescence excitation spectra exhibiting several Stark splittings revealed a complex dependence upon temperature. The largest excitation cross section in the third excited state was 1.65 x 10(-20) cm(2) at an excitation wavelength of 809.4 nm when measured at 77 K. This value is roughly three times larger than the cross section in the second excited state at 4.8 x 10(-21) cm(2) when pumping at 983.0 nm. The Er-related photoluminescence was reduced between 1.5 and 4.8 times when going from 77 K to room temperature, except when pumping around 998 nm. At this excitation wavelength the room temperature photoluminescence was stronger by a factor of 1.26 compared to that at 77 K.