Nano-EBIC analysis: An attempt to describe the surface recombination effects by the modified Donolato probability

Donolato minority carrier collection probability [Sol. Stat. Electron. 28, (1985) 1143-115] is used to describe the surface recombination effects between zero and infinite values of the surface recombination velocity. The probability function is modified for a nano-electrode. An opening angle and a “specific” length are introduced. The opening angle leads to the emerged charge to “see” the electrode, and the “specific” length describes an average distance travelled by the charge at the surface sample before being collected by the nano-contact. Results show that both minority carrier effective diffusion length and collection efficiency maximum increase when the “specific” length is increased. The effective diffusion length varies from 0.3 μm for infinite velocity to 0.9 μm for velocity zero. The latter is 10% smaller than the bulk diffusion Length because of both the nano-scale contact and the bi-dimensional diffusion space which affect the collection probability, and hence the collection efficiency profile.