Double-hump diffusion profiles of copper and nickel in germanium wafers yielding vacancy-related information

Diffusion of Cu and Ni into Ge was investigated between 700 and 900 degrees C with the aid of rapid isothermal lamp annealing and spreading-resistance profiling. Using row-dislocation-density single-crystal Ge wafers with a b ackside gold layer, we observed typical double-hump diffusion profiles of b oth Cu and Ni. These profiles can be described within the dissociative mode l by taking into account that the front surface acts as source for both vac ancies (V) and Cu or Ni while the back surface combines the V-source featur e with a Cu, Ni-sink property. Profile fitting yields data regarding the V- assisted Ge self-diffusion coefficient and the equilibrium concentration of vacancies as a function of temperature. (C) 2000 American Institute of Phy sics. [S0003-6951(00)01231-6].