Evolution of epilayer tilt in thick In Ga1−As metamorphic buffer layers grown by hydride vapor phase epitaxy

Abstract

a b s t r a c tTilt behavior in thick In x Ga 1 À x As metamorphic buffer layers (MBLs) grown by hydride vapor phase epitaxy (HVPE) was measured by high-resolution reciprocal space mapping.Step-graded and continuously-graded structures, grown on nominally (001) oriented GaAs substrates, were analyzed. Tilt was measured as a function of position in a step-graded MBL. It was found that the tilt was strongest near the edges and tended to point toward the sample center.Step-grading induced a nearly linear tilt increase with x InAs , while tilt increased slowly below x InAs $ 0.10 then increased more sharply with In concentration in continuously-graded samples. The tilt behavior could be described by a model in which the tilt is attributed to imbalances in dislocations that result from cross-slip within a glide length of the sample edge. This finding implies that dislocation multiplication by cross slip is an important strain relief mechanism during the growth of these MBLs. Strategies for minimizing tilt in HVPE MBLs are discussed.

High-Power, High-Efficiency Red Laser Diode Structures Grown on GaAs and GaAsP Metamorphic Superlattices

“…Each of these layers resolve as distinct peaks, indicating that the MSL relaxes to a strain-balanced equilibrium in each stage with a common in-plane lattice constant throughout that stage. In addition to a reduction in lattice constant, the MSL layers have a measurable tilt in the direction of the substrate miscut, which is consistent with previous MBL growth studies [14,15]. Barrier Well…”

“…Each of these layers resolve as distinct peaks, indicating that the MSL relaxes to a strain-balanced equilibrium in each stage with a common in-plane lattice constant throughout that stage. In addition to a reduction in lattice constant, the MSL layers have a measurable tilt in the direction of the substrate miscut, which is consistent with previous MBL growth studies [14,15] The in-plane and out-of-plane lattice constants for individual layers of the 4-stage MSL were extracted from the RSM data shown in Figure 8, and the parameters are summarized in Table 2. The maps reveal a high intensity substrate peak, four main peaks thought to correspond to the net material composition of each MSL stage, and eight satellite peaks corresponding to the wells and barriers of each MSL stage.…”

Tilt investigation of In(Al,Ga)As metamorphic buffer layers on GaAs (001) substrate: A novel technique for tilt determination

“…As the tilt is closely related to the strain relieving dislocation, the magnitude and direction of the crystallographic tilt contain information on the nature of the lattice relaxation process. Tilt has been found to vary with the substrate position so, the measurement has been performed at the center of the wafers for all samples. Magnitude (α0) and direction (φta) of the tilt, extracted from the HRXRD measurement data, have been summarized in Table .…”

Low-Cost Approaches to III–V Semiconductor Growth for Photovoltaic Applications

“…Increasing InCl was found to decrease the growth rate of the buffer layers . They later identified factors controlling film tilt over the growth of multiple MBLs as well as optimum growth temperatures . Higher-order III–V’s also have potential applications as top cells; recently, the NREL HVPE system was used to demonstrate In 1– x Ga x As 1– y P y for such a purpose .…”