Dopant profile model in a shallow germanium n+/p junction

Abstract

A challenging issue is to estimate the n-type dopant profiles and, consequently, their diffusivities in shallow Ge n+/p junctions because of their abnormal dopant profiles that do not follow conventional Gaussian-distribution-based diffusion theory. In order to fit the abnormal dopant profiles in shallow junctions, what are due to (1) fast and asymmetric diffusion of n-type dopants and (2) dopant pileup caused by surface back-scattering phenomenon, we propose a new profiling function and verify it by using a fitting algorithm based on the least-squares method. Through this fitting algorithm, we estimate the diffusivity and peak-position values from the raw dopant profile data, and we provide the experimental diffusivity equations as a function of the annealing temperature.