X-ray diffraction studies of thermal treatment of GaAs/InGaAs strained-layer superlattices

Abstract

We analyze in this paper the effect of thermal treatment on structural properties of GaAs/InGaAs strained-layer superlattices grown by molecular beam epitaxy. The superlattices are analyzed using double-crystal x-ray rocking curves. In order to model the satellites intensity variation as a function of the heat treatment time at a temperature of 850 °C, we have calculated the structure factors of the superlattices, taking into account both composition and lattice spacing modulation. The latter is found to be more influent in the calculation in this particular case. The deduced values of the diffusion coefficient, about 2×10−18 cm2/s, is discussed and compared to those determined on GaAs/AlAs structures.

Interdiffusion in GaAs(1-x)Sbx/GaAs superlattices studied with high-resolution x-ray diffraction and secondary ion mass spectroscopy

“…The intensities of the fringes for such a superlattice can also increase during a diffusion experiment. 11 In our case, a dynamical calculation allows an easier comparison of experiment and simulation, because some superlattice reflections are close to the strong ͑004͒ substrate reflex. 8 Both methods yield similar values for the interdiffusion coefficients.…”

“…8,9 A quantitative evaluation requires comparing the measured rocking curve with calculated curves. 10,11 Whether the kinematic approximation for the calculation is sufficient or a dynamical calculation is needed, normally cannot be predicted in advance. It has to be checked for each superlattice structure investigated.…”

Structural and optical properties of InAs–GaAs quantum dots subjected to high temperature annealing

“…10 X-ray diffraction studies of thermal treatment of InGaAs-GaAs strained-layer superlattices yielded diffusion coefficient values in the range between 8.0ϫ10 Ϫ18 and 8.0ϫ10 Ϫ20 cm 2 s Ϫ1 depending on temperature ͑900-850°C͒. 11 These values are close to observed for the AlGaAs-GaAs case. 10 Much larger diffusion coefficients (10 Ϫ15 -10 Ϫ16 cm 2 s Ϫ1 for the 850-950°C range, respectively͒ were found in the photoluminescence ͑PL͒ studies of InGaAs-GaAs quantum wells ͑QWs͒ subjected to pulsed lamp annealing.…”

“…On the other hand, high temperature annealing can potentially introduce severe changes in the QD shape, size, and composition due to possible interdiffusion processes. [10][11][12][13][14] These effects should be either strongly avoided or, on the opposite, can be used intentionally to modify the properties of the QD structures.…”

Schottky enhancement of contacts to n-(In0.52Al0.48)As using PdAl as a metallization

“…These data are not available for (In,Al)As but are available for (In,Ga)As. [20][21][22] Because the lattice parameter of GaAs is the same as that of AlAs, it is reasonable to assume that the interdiffusion coefficient of (In,Al)As is approximately the same as that of (Ga,In)As. The diffusion coefficients for ␤Ј-Pd(In,Al) were recently determined by Lin 12 and Lin et al 23 at 850°C and 1,000°C.…”