Structural and electrical characteristics of InGaAsN layers grown by LPE

Crystallographic and transport properties of nominally undoped and Sn-doped InGaAsN layers grown by low-temperature LPE have been studied and related to the growth conditions. In the case of lattice matching, flat and uniform mirror-like layers of 8-10 mu m in thickness are obtained. The compositions of the layers under study have been determined by combination of X-ray microanalysis and X-ray diffraction methods to be In0.035Ga0.065As0.086N0.014. The lattice mismatch between layer and substrate Delta a(t)/a(s) calculated from X-ray diffraction curves is less than -7 x 10(-4) for all samples. The layers grown at lower epitaxy temperatures exhibit the highest crystalline quality, better lattice match and better homogeneity. This is in good agreement with the results of morphological study by atomic force microscopy which show root mean-square surface roughness of 0.18 nm for the best layers. CV and Hall measurements reveal that intentionally undoped InGaAsN layers are n-type with free carrier concentration about one order of magnitude higher in comparison to layers not containing nitrogen and high electron mobility values over 2000 cm(2)/Vs. A dramatic reduction in the free carrier concentration and slightly increase in mobility are observed for Sn-doped InGaAsN layers. (C) 2012 Elsevier B.V. All rights reserved.