Techniques are described for the preparation of multiple junction structures in semiconductors by solid state diffusion of impurities from a region of a doubly doped crystal into an adjacent region of different impurity concentrations. The change in impurity concentrations from one region to the other is achieved initially by surface melting and regrowth, and is later modified by diffusion. Conditions which must be imposed on the doping levels, segregation coefficients, and diffusion constants of the doping materials employed will be discussed.p‐n‐p, n‐p‐n, andn‐p‐n‐pstructures have been fabricated in germanium.