Investigation of Bragg surface diffraction in semiconductors and epitaxic structures by reciprocal-space analysis

Abstract

Bragg surface diffraction (BSD) is a special case of three-beam diffraction, where the secondary beam is scattered in the surface-parallel direction. Under the BSD condition, the surface-detour re¯ection (secondary plus coupling re¯ections) transfers some of the secondary-beam intensity into the monitored primary beam. The extinction regime in which such transfer takes place depends on the crystalline perfection of the surface. Based on this fact, the mapping of the BSD pro®le, in an 3:9 scan technique, has been proposed [Morelha Ä o & Cardoso (1996). J. Appl. Cryst. 29, 446± 456] as a method to obtain information on the in-plane crystalline quality of the surface. With the X-ray optics for BSD mapping, the diffracting surface thickness that de®nes the pro®le could not be measured or compared with those under conventional Bragg diffraction. In this report, the BSD using a triple-axis diffractometer is investigated. Reciprocal-space mapping of the Bragg re¯ection (primary re¯ection) was performed in and out of the BSD condition. It reveals the diffracting surface thickness of BSD in GaAs and Si substrates. The triple axis was also used to investigate the BSD in the SiGe multiple quantum well, and it has demonstrated the existence of effective satellite peaks for such structures.

Characterizing the thickness dependence of epitaxial GaN grown over GaN nanocolumns using X-ray diffraction

“…Therefore, depending on the incident angle (skew angle) of the X-ray beam, the three-beam XRD signal mainly comes from a certain depth of the sample. In other words, the three-beam XRD technique has the capability of monitoring relative crystal properties at different sample depths [8]. For the XRD measurement in the (0 11 3)/(0 1 1 2 ) plane, which is the case of this study, the relationship between the measurement sample depth, t, and the skew angle, y, can be derived to give [9] t ¼ 1 u ½ sin y ð0 0 0 1Þ cos y 1 þ sin ðy ð0 11 3Þ þ y ð0 11 3Þ=ð0 0 0 1Þ Þ cos y 2…”

Coalescence overgrowth of GaN nanocolumns on sapphire with patterned metal organic vapor phase epitaxy

“…First, we used a three-beam XRD technique for plotting the rocking curves in the ͑01-13͒/͑0-11-2͒ plane at various depths by changing the x-ray incident angle. [15][16][17][18] In such a measurement, depending on the incident angle of the x-ray beam, the XRD data mainly come from a certain depth of the sample. In the second depthdependent XRD method, a two-beam technique is used for calibrating the screw dislocation density, edge dislocation density, and the lateral domain size based on the equation 19…”

Strain field of InAs QDs on GaAs (001) substrate surface: characterization by synchrotron X-ray Renninger scanning

“…(5) must be calculated forx = (1, 1, 0)/ √ 2,ŷ = (1, 1, 0)/ √ 2 andẑ = (0, 0, 1), i.e., S x = (h + k)/(a √ 2), S y = (−h + k)/(a √ 2) and S z = 1/c. The observed tetragonal deformation ν ≃ 1.77 × 10 −4 , corresponds to an average value in a shallow layer just below the surface, not thicker than 0.3 µm, 3 where the induced strain due to the InAs QD is significant. Although the InAs epitaxial growth generates an expansive stress in the substrate lattice under the QDs, the adjacent regions are compressed as schematically illustrated in Fig.…”