X-ray Rocking Curve Measurements Research Articles

On the Increased Sensitivity of X-Ray Rocking Curve Measurements by Triple-Crystal Diffractometry

On the Increased Sensitivity of X-Ray Rocking Curve Measurements by Triple-Crystal Diffractometry

Selective reactive ion etching of silicon dioxide : J. S. Chang. Solid St. Technol. 214 (April 1984)

Cubic silicon carbide (β-SiC) films have been grown epitaxially on silicon-on-sapphire (SOS) substrates by chemical vapor deposition. A fresh layer of silicon is first deposited in situ on the SOS substrate at approximately 1050°C. The silicon layer is then carbonized while being heated to 1360°C. The β-SiC layer is grown at 1360°C using silane and propane as sources. β-SiC films can also be grown directly on the SOS substrate without utilizing a fresh silicon layer. Deposition of β-SiC films on silicon-on-insulator (SOI) substrates has also been accomplished with slight modification of the growth parameters described above.The β-SiC films have been characterized by IR reflectance spectroscopy, optical microscopy and electron microscopy. Typical films are 7 μm thick and have a specular surface with some physical features. Electrical transport properties as determined by the Van der Pauw Hall method show the β-SiC films to be p-type while those grown on SOI were n-type. X-ray rocking curve measurements were obtained to determine the crystalline quality of the films. In addition, preliminary optical characterization of the films has been performed.

Strain and Damage Measurements in Ion Implanted AlxGa1−x As/GaAs Superlattices

AbstractStrain measurements in AlxGa1−x As/GaAs superlattices have been carried out before and after Si ion implantation. For doses up to 5 × 1015 cm−2, no atomic intermixing of the sublayers is observed by backscattering spectrometry. However, with x-ray rocking curve measurements, significant changes in the strain profiles are detected for implantations with doses as low as 7 × 1012 cm−2. Interpretation of the rocking curves suggests that low-dose implantations release strain in the AlxGa1−x As sublayers. The strain profile recovery of the implanted samples, upon annealing at ∼ 420°C, implies that the damage caused by implantation is largely reversible.

GaxIn1− xP Liquid phase epitaxial growth on (001), (111)a, and (111)b GaAs substrates

Ga x In 1- x P alloy layers were grown on (001), (111)A, and (111)B GaAs substrates at 785 and 740°C by liquid phase epitaxy. These layers were characterized by means of X-ray rocking curve and photoluminescence (PL) measurements. The lattice mismatch Δa ⊥/ a 0 between the Ga x In 1- x P layer and the GaAs substrate normal to the wafer surfaces varies linearly with the Ga atom fraction in the growth melts, for growth on substrates with the three orientations. The distribution coefficient of Ga ( K Ga) depends strongly on the orientations ( K (001) Ga > K (111)A Ga > K 111)B Ga). The PL peak energy versus Δa ⊥/ a 0 data lie on the same straight line for all layers on the (001), (111)A, and (111)B substrates. For layers on the (001) and (111)A, the half-widths of the X-ray rocking curves and the PL spectra were very sharp and the surfaces of the layers were very smooth, in comparison with those for the (111)B layers. The crystalline quality of the (001) and (111)A layers, therefore, is considered to be better than that of the (111)B layers. For growth on the (001) and (111)A faces at 740°C, the quality of the grown layers was better than those grown at 785°C.

Investigation of crystallographic properties of thin germanium crystals grown on silicon substrates by chemical vapor deposition

The quality of germanium crystals deposited from the gas phase by chemical vapor deposition using pyrolytic decomposition of GeH 4 in a helium atmosphere at various growth temperatures on silicon substrates was determined. X-ray diffraction and rocking curve measurements proved to be very useful in determining the degree of preferred orientation of the germanium deposit, since they distinguish clearly between the reflections of the thin germanium deposited layer and those of the thick silicon substrate. Therefore they permit fairly accurate calculations. Laue measurements, in this case, proved to be unsatisfactory because of inadequately low resolution. The results show that a preferred orientation of germanium crystallites in the layer of up to 99.9% was reached.

Determination of notch-tip plasticity by X-ray diffraction and comparison to continuum mechanics analysis

Dislocation-free silicon crystals of ({\bar 2 \bar 1 \bar 1}) orientation with a hyperbolic notch, subjected to tensile deformation at 1073 K, were used as model material for the analysis of the induced plastic zone. The results obtained by X-ray topography and X-ray rocking-curve measurements were compared to theoretical calculations and predictions based on continuum mechanics. Good agreement between experiment and theory was obtained regarding the shape of the plastic zone, the contribution of the active slip systems to the size of the plastic zone and the direction of the maximum plastic strain trajectory in the zone. Discrepancies between experiment and theory regarding the symmetry relation of the plastic zone lobes and the dislocation density near the notch tip were attributed to the interactions and resulting work-hardening. These aspects were not taken into account in calculations of continuum mechanics.

A model for interpretation of X-ray rocking curve half-widths in SOS

A systematic variation in the full-width-at-half-maximum intensity of the X-ray rocking curve with rotation about the diffraction plane normal is found for silicon on sapphire (SOS). This variation has mirror symmetry which is related to the crystal structure of the sapphire substrate even though the X-ray diffraction is from the heteroepitaxial silicon layer only. A quantitative model based on the defect structure of SOS films is developed to interpret the rotational variation in the rocking curve half-width. This model assumes that for (001) silicon on (1 1 02) sapphire the silicon film is partitioned into tilted mosaic plates (TMP) of perfect crystal which are bounded by the two [111] planes which contain the majority of the microtwins and stacking faults in the silicon layer [10,11]. Both the relative misorientation of these plates and the plate thickness contribute to the diffraction peak broadening. The deviation parameter, η, is found to be a minimum in the direction of least lattice mismatch between the silicon and sapphire crystals and is two-fold symmetric. Diffraction peak broadening due to the geometry of the TMP is wavelength dependent and has mirror symmetry. Using this model more information may be extracted from X-ray rocking curve measurements on SOS about the silicon defect structure. These measurements may then be used to provide a greater understanding of the effect of material processing parameters on the defect structure of SOS.