Fig. 1. Carrier Generation-Tip Collection Scanning Electrochemical Cell Microscopy (CG-TC SECCM). (a) Minority carriers are generated within a semiconductor through localized illumination and diffuse outward within the material. As carriers reach a probe positioned some distance away, they can be utilized to drive an electrochemical reaction. (b) Idealized 2D carrier profile resulting from illumination with a Gaussian beam. (c) Expected CG-TC SECCM response corresponding to this carrier profile. Dashed lines represent limits corresponding to carrier transport within the semiconductor (i_ct) and the mass transfer of redox species in the electrolyte solution (i_mt). The calculations in (b) and (c) were carried out for a system with N₀ = 3.2 × 10¹² s⁻¹, t_c = 1 ns, α = 10⁵ cm⁻¹, σ₀ = 0.725 µm, w = 50 nm, L = 3 µm, r₀ = 150 nm, θ_p = 10°, D_r = 2 × 10⁻⁵ cm² s⁻¹, and = 100 mM.