Degree of Polarization of Cathodoluminescence from a GaAs Facet in the Vicinity of an SiN Stripe

Abstract

Measurements of the cathodoluminescence (CL) and the degree of polarization (DOP) of (CL) from the facet of a GaAs substrate and in the vicinity of a SiN stripe are reported and analyzed. The deformation induced by the SiN stripe is estimated by fitting the measured DOP to 3D finite element method (FEM) simulations. The deformation is found to be more complex than an initial condition of biaxial stress in the SiN. A ratio of fit coefficients suggests that the dependence of DOP on strain is described by equations presented in Appl. Opt. 59, 5506–5520 (2020). These equations give a DOP that is either proportional to a weighted difference of the principal components of strain in the measurement plane, or proportional to the shear strain in the measurement plane, depending on the chosen orientation of the measurement axes.

Degree of Polarization of Cathodoluminescence from a (100) GaAs Substrate with SiN Stripes

“…The CL measurement system, which is an Attotlight Allalin spectroscopy platform, is described in Ref. [41]. In the work reported here, the beam energy E o was increased to 8 keV from 5 keV and the surface under measurement was the top surface (i.e., a (100) surface) rather than a facet.…”

“…These results are summarized in Table 6 and are compared to results obtained for CL measurements of the DOP or ROP at the facet using a 5 keV electron beam [41] and for PL measurements [22,48]. The minimum detectable change in DOP for light from under the SiN is approximately δ SiN, 8 keV (1) ≈ 2 × 10 −2 , which is twice the value found for similar measurements from the GaAs that is to the left and right of the SiN stripe.…”