图11. 非对称反射方法测定时角度差\mathrm{\Delta }\theta={\theta }_{\mathrm{L}}-{\theta }_{\mathrm{S}}和\mathrm{\Delta }\tau={\tau }_{\mathrm{L}}-{\tau }_{\mathrm{S}}的成因

Fig.11. Origin of the angle differences Δθ=θ_L-θ_S and Δτ=τ_L-τ_S when measuring asymmetric diffraction of epitaxial layer and substrate (Δθ—the difference of Bragg angle between epitaxial layer and substrate, Δτ—the difference of tilt angle between epitaxial layer and substrate, θ_L—Bragg angle of asymmetric diffraction for epitaxial layer, θ_S—Bragg angle of asymmetric diffraction for substrate, τ_L—the angle between asymmetric diffraction plane of epitaxial layer and surface of sample, τ_S—the angle between asymmetric diffraction plane of substrate and surface of sample, d_L—the plane spacing of asymmetric diffraction for epitaxial layer, d_S—the plane spacing of asymmetric diffraction for substrate, a_S—the lattice parameter of substrate, a_{\mathrm{L}}^{\mathrm{p}}—the lattice parameter of layer in parallel direction, a_{\mathrm{L}}^{\mathrm{v}}—the lattice parameter of layer in vertical direction)