Surface Phase Separation and Ordering in Compound Semiconductor Alloys

Abstract

The orientation dependence of phase separation has been examined in detail in InGaAsP layers grown by liquid phase epitaxy on (001), (110), (111)In and (123) InP substrates. It is shown that phase separation is two-dimensional in nature and does not occur along the growth direction for the cases examined. Further, phase separation takes place along the soft directions lying in the growth plane. These results very strongly suggest that phase separation evolves at the surface while the layer is growing.CuPt-type ordering characteristics of InGaAsP layers are presented. In addition, the Influence of growth temperature and growth rate on domain sizes have been investigated in GaInP2 layers. A model has been proposed to rationalize the formation of domains and involves steps present on the surface. Results suggest that ordering like phase separation occurs at the surface while the layers is being deposited. It is inferred that the two microstructural features evolve concomitantly at the surface during layer growth.

A TEM Microstuctural Study of the Factors Affecting the Compositional Modulation in GaInAsSb/GaSb Films

“…Samples #1 and #2, which were grown under higher susceptor rotation frequency (9 rpm), had lower VCM periods (3.4 and 3.5 nm) than those grown at 6 rpm, which had higher VCM periods (around 4.6 nm). Thus, our results indicate that the VCM is correlated to the susceptor rotation period and should be attributed to inhomogeneities in the reactor chamber [6] On the other hand, the LCM, with periods ranging in tens of nanometers, is probably caused by a strain field existing at the epitaxial surface [7,8]. This is more possible because bulk diffusion coefficients of the constituting elements are too low to explain the length scales of the observed compositional modulation [8].…”

Self‐Assembled InAs Quantum Dots on InGaAsP/InP(100) by Modified Droplet Epitaxy in Metal–Organic Vapor Phase Epitaxy around the Telecom C‐Band for Quantum Photonic Applications

“…For the In x Ga 1-x As y P 1-y /InP system, a phase separation at the surface during epitaxial growth exists, also referred to as lateral composition modulation (LCM). [30][31][32][33] Specifically, LaPierre et al [30] found that a preferential sticking of P atoms to Ga sites and of As to In takes place, which results in the formation of GaP and InAs-rich areas. They also found that LCM is strongly dependent on the InGaAsP surface orientation and composition, being more pronounced for the (100) orientation and for 1.3 μm bandgap wavelength, which corresponds to the case investigated here.…”

Quantification by optical absorption of the coarse modulation observed by transmission electron microscopy in InGaAs layers grown on InP(100)

“…Of course, a thin homogeneous strained layer would be unstable and will tend to relax the strain by buckling. In particular, several authors [15] argue that the buckling is promoted by the existence of the fine modulation. They associate the coarse modulation to this buckling.…”