Influence of growth temperature on the structural and optical quality of GaInNAs/GaAs multi-quantum wells

Abstract

This work focuses on the influence of the growth temperature on the structural and optical quality of GaInNAs/GaAs and GaInAs/GaAs multi-quantum wells with similar lattice mismatch, studied by transmission electron microscopy and photoluminescence. We have found compositional fluctuations in all the GaInNAs samples, which vary from negligible to very strong over the temperature range studied (360–460 °C). In comparison, at the same growth temperature, GaInAs heterostructures appear more homogeneous. It is proposed therefore that the introduction of N in the structure could be responsible for the enhanced phase separation. A broadening of the photoluminescence peak in GaInNAs structures when raising the growth temperature has also been found associated with the increase in composition fluctuations. Moreover, a kinetically limited Stranski–Krastanow growth mode has been observed in both GaInAs and GaInNAs structures, taking place at lower temperature in GaInNAs quantum wells. We suggest that the enhancement of this growth mode is a consequence of the increased phase separation. The influence of the introduction of N into the GaInAs alloy on the compositional fluctuations and 3D growth mode is discussed.