Structural properties of (GaIn) (NAs)/GaAs MQW structures grown by MOVPE

The structural properties of (GaIn)(NAs)/GaAs multiple quantum well structures (MQW) have been evaluated by means of high-resolution X-ray diffraction (XRD) in combination with simulation using dynamic modelling and TEM studies. This metastable material system has been grown successfully by non-equilibrium MOVPE at low substrate temperatures using the efficient group V precursors 1,1-dimethylhydrazine (UDMHy) and tertiarybutylarsine (TBAs). High structural quality of the quaternary material has been achieved for both lattice matched and strained layers for In and N concentrations up to 30% and 4%, respectively. Due to the extreme non-equilibrium growth conditions there is no indication of phase separation effects. A novel morphology transition presumably caused by a microscopic strain effect has been established experimentally in compressive-strained quaternary (GaIn)(NAs) when exceeding a critical N-content of about 4.5%. Possible explanations for this effect are discussed.