On overannealing of GaIn(N)As/Ga(N)As multiple quantum wells grown by molecular beam epitaxy

Abstract

Evolution of photoluminescence (PL) and strain is investigated in GaIn(N)As/Ga(N)As multiple quantum wells (MQWs) over a wide range of annealing temperatures from 700 to 900 °C. We observe two optimal annealing temperatures (Topt) that result in reduced PL linewidth and increased PL intensity irrespective of the thermal-induced strain relaxation. The decrease of PL intensity accompanied by peak splitting after the first Topt is mainly associated with the deterioration of the GaAs cap layer and the optical quenching after the second Topt is due to the overannealing-induced degradation of the bottom QWs. The strain relaxation in GaInAs/GaAs MQWs at elevated temperatures, which gives rise to extrinsic defects at the bottom of the MQWs stack, only plays a minor role in PL evolution, while no strain relaxation is observed in GaInNAs/GaNAs MQWs.