Specific structural and compositional properties of (GaIn)(NAs) and their influence on optoelectronic device performance

We have grown (GaIn)(NAs) lattice-matched bulk as well as compressively strained multi-quantum-well structures by metal-organic vapour-phase epitaxy (MOVPE) suitable for either solar cell or laser applications, respectively. By applying a specific novel TEM dark-field technique columnar strain fields, which are possibly caused by chain-like N ordering in the samples, have been detected. Valence force field calculations show that indeed these chains are energetically stable in Ga(NAs). This chain-like ordering can be dissolved in (GaIn)(NAs), however, upon appropriate annealing, as verified experimentally. On the other hand we find that device performance especially of lasers is limited by carbon impurities in the active (GaIn)(NAs) region of the lasers. The strong affinity of N–C results in an enhanced incorporation of C if the N content in the material is increased. The paper also shows the sources of C incorporation in (GaIn)(NAs) MOVPE growth and how its incorporation can possibly be avoided.