Characterization of InGaN/GaN and AlGaN/GaN superlattices by X‐ray diffraction and X‐ray reflectivity measurements

Abstract

The commercial significance of superlattice structures is increasing due to greater demand of optoelectronic devices, such as the light emitting diode (LED). In order to optimize these devices, an accurate and reliable characterization method is needed. This paper describes in detail the characterization of superlattices with X‐ray scattering techniques. The thicknesses of the individual layers are determined by X‐ray reflectivity (XRR) measurements and the state of strain, the lattice constants and the compositions of ternary compounds by X‐ray diffraction (XRD) measurements. The method is non‐destructive, and yields unique results, unlike characterizations based on simulation of symmetric XRD scans. These simulations were used for verification of results. The method was tested on InGaN and AlGaN superlattice structures. The measured and simulated parameter values agreed very well. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low energy electron beam induced damage on InGaN/GaN quantum well structure

“…The thickness of the InGaN QW and of the GaN CL were measured by x-ray reflectivity (details elsewhere). 10 Areas of 700 lm  700 lm of the sample surface were exposed to an e-beam using a Zeiss Supra 40 SEM varying the exposure dose from 0 to 500 lAs/cm 2 and e-beam energy from 5 to 20 keV. The lower limit of 5 keV results from the SEM system being unable to measure the beam current accurately under 5 kV acceleration voltages.…”

X‐ray reflectivity method for the characterization of InGaN/GaN quantum well interface

“…X‐ray reflectivity (XRR) is a powerful technique for thin film characterization () which is generally employed to determine the thickness of QWs . However, it can also be used to extract information relative to the interface of thin layers .…”

Combined cross sectional scanning tunneling microscopy and high resolution x-ray diffraction study for quantitative structural descriptions of type-II superlattice infrared detectors

“…[5][6][7] Typically, the SL period is estimated from the satellite peak separation, and the average SL lattice parameters are estimated from the positions of the zeroth order peaks of the specular reflections. More detailed structural information can be obtained by dynamical simulation of the XRD spectra using initial parameters from the SL design.…”