Optical characterization of orientation-patterned GaP structures by micro reflectance difference spectroscopy

Abstract

The integration of zincblende semiconductors on silicon demands for a real-time control of the crucial steps of epitaxial growth process at a microscopic level. Optical probes, being non-invasive, are very useful in monitoring such processes at a microscopic level. By using the reflectance anisotropy technique with microscopic resolution (μ-RD/RA), which detects the difference in reflectance for two orthogonal crystal directions, we measured the optical anisotropies below and above band gap of orientation-patterned GaP structures deposited on both Si(100) and GaP(100) vicinal substrates. We have developed a physical model to describe the line shape of the spectra below and above the fundamental gap of GaP. By using this model, we have successfully analyzed μ-RD/RA spectra, and we were able to do anisotropy topographic maps of the surface and buried interface, which are consistent to those measured with scanning electron microscopy.

Microscopic optical anisotropy of exciton-polaritons in a GaAs-based semiconductor microcavity

“…The reflectance anisotropy spectroscopy technique at microscopic scale (μ-RAS) has been shown to be a powerful optical technique for the characterization of surfaces and interfaces [10][11][12]. For example, using μ-RAS, it is possible to realize detailed spatial mappings of in-built strain at a buried interface [13], or to characterize surface defects [11]. The technique is noninvasive and can be used in air or under vacuum conditions.…”

In Situ Characterization of Epitaxy

“…By comparing spectra above and below the band edge of GaP (2.78 eV), an anisotropy FIGURE 29.18 In situ RAS of Ge (100):As 6 with predominant (2 Â 1) (red) and (1 Â 2) (green) surface reconstruction domains where dimers are oriented parallel (Ge (100):As jj ) or perpendicular (Ge (100):As t ) to the step edges, respectively. topographic map of the surface and buried interface could be generated, as shown in Figure 29.21 [51]. The insets illustrate the major As dimer orientation on the surface with respect to the step edges.…”

“…An excellent early review of RHEED appeared in 1990 by Joyce [54], a pioneer in both MBE and the RHEED technique.A brief description of the basis of the technique is given here (Figure 29.22). [51]. The intensity of the beams contains extensive information on the perfection and crystalline structure of the surface.…”

Thickness Determination and Control in Protein-Based Biomaterial Thin Films

“…However, they can be time-consuming and invasive methods, since measuring film thickness with these techniques often involves scratching the samples to create a step between the film and the exposed substrate. , Finally, other noninvasive techniques, such as SPR, are suitable for nonuniform small-area films, but their use is restricted to samples on metallic substrates and requires specialized experimental setups. In contrast, microtransmittance and microreflectance spectroscopy techniques offer a fast, accurate, noninvasive method to characterize the thickness and uniformity of thin films, even for nonuniform films or samples with small surface areas. − These techniques provide spatially resolved information with micrometer resolution and require relatively simple, nonsophisticated instrumentation, and data analysis. Specifically, microreflectance is suitable for use with samples on transparent and nontransparent substrates and has been widely applied for the thickness determination of different inorganic and organic thin films …”