Figure 2
Simulation results for the truncated photocarrier number δNtrunc and the fitted decay length Lfit under pulse excitation. (a-c) Profiles of δNtrunc with varied parameters such as (a) ambipolar diffusion length La, (b) surface recombination velocity of the GaAs/air interface S, and (c) pumping density P, respectively. (d) Relation between the fitted decay length and the given ambipolar diffusion length with varied excitation spot size. The x = y line is shown as the dashed line for clarity. (e) Fitted decay length as a function of the surface recombination velocity with varied carrier lifetime. (f) Fitted decay length as a function of the pumping density. The profiles in (a-c) are offset vertically for clarity. The exponential functions with different given La are shown as the dashed lines in (a-c) for comparison. The given ambipolar diffusion lengths are shown in (e,f) as the dashed lines for clarity. The pulse excitation conditions are the same as those in Fig. 1. Da is 20.4 cm2/s, τ is 254 ps, C is 7 × 10−30 cm6/s, and S at x = 0 boundary between GaAs and air is 105 cm/s unless otherwise specified.
