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

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 degrees C. We observe two optimal annealing temperatures (T-opt) 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 T-opt is mainly associated with the deterioration of the GaAs cap layer and the optical quenching after the second T-opt 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. (c) 2007 American Institute of Physics.