Photoluminescence of InxGa1-xAs-GaAs strained-layer superlattices

Photoluminescence of In_xGa_1-xAs-GaAs strained-layer superlattices (SLS's) grown by molecular beam epitaxy (MBE) is investigated. Highly strained SLS's composed of layers differing in their bulk lattice constants by as much as 2.7% are examined over the temperature range 20K-300K. Photoluminescence (PL) spectra for several In_0.28Ga_0.72AsGaAs SLS's are presented, providing data relating effective band gap and PL intensity to temperature and layer thickness. These data suggest a critical (maximum) alloy layer thickness for optical quality material in the range of 80å-100å for crystals with x = 0.28 and an In_xGa_1-xAs/GaAs layer thickness ratio of L_z/L_B = 1.3. Results of PL experiments on In_0.38Ga_{0 62}As-GaAs SLS's are also presented, and the effects of lattice misfit at the SLS/substrate interface upon the optical quality of these SLS's is examined.