Method of introducing impurity species into a semiconductor structure

Abstract

A thin film bilayer composite source comprises a deposited impurity source layer, e.g. Si or Sb, heavily doped with a diffusion enabling agent, e.g. As, and capped with a passivating layer, e.g. Si.sub.3 N.sub.4, SiO.sub.2, AlN or SiO.sub.x N.sub.y. In a preferred embodiment, a thin film bilayer composite source comprises a Si layer on the surface of said structure vapor deposited at a temperature in excess of 500.degree. C. in the presence of a source of As to hevily dope the layer in the range of 5%-20% atomic weight and a thin cap layer of Si.sub.3 N.sub.4 deposited on the Si layer at a temperature in excess of 500.degree. C. having a thickness only sufficient to prevent the outdiffusion of Ga and As, which thickness may be about 400 .ANG.-700 .ANG.. An important aspect of the employment of this bilayer composite source as a diffusion source for III-V structures is that the composite source is initially deposited at high temperatures, above 500.degree.0 C., i.e., at temperatures that are into the range of annealing temperature, e.g. about 500.degree.-900.degree. C., preferably 700.degree.-850.degree. C., so that cracking due to thermal strain or compressive stress will not occur on subsequent high temperature annealing thereby providing reproducible, uniform impurity diffusion into III-V structures. A particular application of bilayer composite source is in impurity induced disordering (IID).