Mg. Meere et al., ASYMPTOTIC ANALYSIS OF SOME 2-DIMENSIONAL DIFFUSION-PROBLEMS, Proceedings - Royal Society. Mathematical and physical sciences, 448(1933), 1995, pp. 213-236
In this paper we discuss two-dimensional surface source and implant pr
oblems for a substitutional-interstitial diffusion model. We present a
symptotic solutions in the limit of the surface concentration of impur
ity (or peak concentration of the implant) being far greater than the
equilibrium vacancy concentration. Using leading order composite solut
ions we plot contours of constant impurity concentration. Some of thes
e contours differ markedly from those of the corresponding linear prob
lem, having the 'bird's beak' shape which is frequently observed in ex
periments. We also discuss a two-dimensional surface source problem fo
r a vacancy model.