INVESTIGATION AND OPTIMIZATION OF INGAAS/INP HETEROINTERFACES GROWN BY CHEMICAL BEAM EPITAXY USING SPECTROSCOPIC ELLIPSOMETRY AND PHOTOLUMINESCENCE

Spectroscopic ellipsometry (SE) has been used to investigate transition layers for InGaAs/InP heterointerfaces. For the case of InGaAs on InP, we have found that the samples can be best modeled by a strained InxGa1-xAs film with the possible presence of a thin interface region (< 15 angstrom). We are unable to conclusively determine the existence of such a thin transition region. For InP on InGaAs, we find clear indications of As contamination in the bulk film, and that the addition of a thin interface region of In0.75Ga0.25As0.5P0.5 improves both the numerical fit and shape of the dielectric response curves, especially around E1 and E1 + delta-1, where the effects of a transition region are most pronounced. However, difficulties in modeling the dielectric response of the contaminated InP film make identification of an interface transition region only speculative at this point. Multiple single quantum well structures have also been grown and analyzed with 7K photoluminescence. The quality of the quantum wells shows strong dependence on the gas switching sequence used at the heterointerfaces. The best switching sequence produced a 0.5 nm well with a 7K FWHM of only 12.3 meV. Multiple quantum wells have also been grown to investigate the uniformity and repeatability of our system. Twenty period MQWs with a well width of 1.6 nm display a 14K FWHM of 7.9 meV.