X-ray rocking curve

One problem with methods that produce polycrystalline or nanocrystalline material is that it is not feasible to characterize electrically dopants in such materials by the traditional four-point-probe contacts needed for Hall measurements. Other characterization methods such as optical absorption, photoluminescence (PL), Raman, X-ray and electron diffraction, X-ray rocking-curve widths to assess crystalline quality, secondary ion mass spectrometry (SIMS), scanning or transmission electron microscopy (SEM and TEM), cathodolumi-nescence (CL), and wet-chemical etching provide valuable information, but do not directly yield carrier concentrations. 

Figure 1.2 Calculated plane wave X-ray rocking curves, (a) Si 004 with CuK i (0.154 nm), FWHM=3.83 arcsec, (b) Si 333 with MoK j (0.071 nm), FWHM=0.73 arcsec, (c) Ge 111 with CuK i, FWF1M=16.69 arcsec, (d) GaAs 004 witih CuK FWHM=8.55 arcsec...

In this chapter we shall see how the basic parameters can be very easily obtained and interpreted from X-ray rocking curves for relatively simple stractures. We define these as good quality substrates (giving rocking curves near the theoretical width) and up to, say, three layers, each at least 0.5 /an thick. Though these are simple, they nevertheless comprise a large sector of the optoelectronics device production and are certainly realistic cases. The discussion will also illustrate maty important principles. In later chapters we shall develop the methods of interpretation of more complex cases. 

FIGURE 1 X-ray rocking curve for the GaN homoepitaxial layer on the highly conductive substrate. 

Fig. 3 (a) Schematic diagram of double-crystal x-ray rocking curve technique (6). 

The available data do not provide a detailed picture of the nature of abrasion damage on germanium and silicon. A complete description would have to explain the effects on various phenomena such as x-ray rocking curves, etching rates, lifetime of minority carriers and conductivity. The measurable effects on the first three of these are felt to about the same depth. (The conductivity data are not directly comparable). 

Etching rate increases may be due to a combination of increased area and dislocation density. The x-ray rocking-curve effects do not require the presence of dislocations, only misoriented material, but they might be caused by dislocations (42). 

Structural characterization of processed Si N was performed by cross-sectional transmission and high resolution electron microscopy techniques (XTEM and HRTEM, respectively). The structure of Si N samples was also investigated by X-ray diffractometry (XRD). The X-ray rocking curves, 20/co scans as well as X-ray reciprocal space maps (RSM) were registrated. 

The control of the tilt and azimuthal angles of (100) faces is important to improve the quality of HOD films. In Ref. [264], the tilt (x) and azimuthal 4>) misorientation angles of the (100) faces were measured by both the X-ray precession method and the X-ray rocking curve measurements for HOD films with thicknesses of 1, 4, 20, and 100 pm, which were made by the three-step process (see Figure 5.3). The results are shown in Figure 11.8. 

For the three film thicknesses, (x) and (0) have their minima when the thickness was 20 pm. The FWHM of X-ray rocking curve for the 100-pm thick HOD film was 3.1°. The fact that (x> and () increased between the film thickness of 20 to 100 pm is apparently in contradiction with the van der Drift s theory [77], in which the orientational order should become better as the film thickness increases. The authors of Ref [264] speculated that this was due to (i) the increase in the... 

Finally, it is noted that the X-ray rocking curve for (111) diffraction line was 2.5°. This value is almost comparable to the corresponding value of HOD films, but much greater than the value of single crystal diamond, 0.03°. Part of the reason for this is that for the diamond-Pt case, the X-ray diffraction picked up the signals from diamonds near the interface, which are more randomly oriented. 

Figure 5. X-ray rocking curves for the (006) reflection solid line, before high pressure annealing dashed line, after high pressure annealing.

Fig. 6.3. Schematic illustration of optical configuration used in X-ray rocking curve analysis...

Figure 5.10 Triple axis (a) symmetric (0002) and (b) asymmetric (1012) X-ray rocking curve FWHM of the GaN films grown on porous SiC. The horizontal axis shows the density of surface pores on various substrates. The dashed lines are drawn as guides to the eye. Reproduced from A. Sagar et al., J. Vac. Sci. Technol. B 21, 1812. Copyright (2003), with permission from the American Institute of Physics...

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