Impact of thermal treatment on the optical performance of InGaN/GaN light emitting diodes

Abstract

This paper describes a detailed analysis of the effects of high temperatures on the optical performance and structural characteristics of GaN-based LED structures with a high threading dislocation density. Results show that, as a consequence of storage at 900 °C in N2 atmosphere, the samples exhibit: (i) an increase in the efficiency of GaN and quantum-well luminescence, well correlated to an increase in carrier lifetime; (ii) a decrease in the parasitic luminescence peaks related to Mg acceptors, which is correlated to the reduction in the concentration of Mg in the p-type region, detected by Secondary Ion Mass Spectroscopy (SIMS); (iii) a diffusion of acceptor (Mg) atoms to the quantum well region; (iv) a reduction in the yield of Rutherford Backscattering Spectrometry (RBS)-channeling measurements, possibly due to a partial re-arrangement of the dislocations, which is supposed to be correlated to the increase in radiative efficiency (see (i))

Laser-induced activation of Mg-doped GaN: quantitative characterization and analysis

“…However, AFM measurements (figure 4) revealed that RTA these three conditions did not result in an increased roughness of the material, since the RMS roughness was found to be in the range between 400 pm and 500 pm. This suggests that the slight increase in Mg concentration for the sample treated for 30 min at 850 • C can be ascribed to a minor back diffusion of Mg. Mg redistribution was reported also in previous reports (see [15] and references therein) at similar temperature levels, indicating the consistency of our results.…”