Structural characterization and elastic strain of InGaN/GaN multiple quantum wells

X-ray diffraction, transmission electron microscopy and Rutherford backscattering/channeling are used to characterize the structure of an InGaN/GaN multiple quantum well (MQW) grown on an Al/sub 2/O/sub 3/(0001) substrate. Using the combination of these measurements, not only the layered structure of the MQW is revealed clearly but also the In content x (0.16) of the In/sub x/Ga/sub 1-/N component can be determined reliably, which is a prerequisite for further determination of the elastic strain of the MQW. X-ray /spl theta/-2/spl theta/ scans of the (0002) and (101~4) diffractions are used to determine the average lattice parameters and of the MQW, consequently the average parallel elastic strain = -0.25% and the average perpendicular elastic strain = +0.13% of the MQW are deduced. The experimental result of / = -0.52 is in good agreement with the value deduced from the elastic constants.