A SOLUTION OF THE DOPING PROBLEM FOR GA DELTA-DOPING LAYERS IN SI

We have studied the incorporation of Ga in silicon during the fabricat ion of delta-doping layers. The delta-function doping profiles were gr own by molecular beam deposition following a solid phase epitaxial gro wth method. Medium-energy ion scattering, secondary ion mass spectrome try, and Rutherford backscattering spectrometry were used to determine the structure and composition of the grown films. The interface veloc ity of the crystallization front and the diffusion coefficient of the impurity atoms-in the Si matrix, both relevant parameters of the growt h process, were measured. Optimum growth conditions were found that yi eld Ga doping profiles of less than 1.0 nm (full width at half maximum ), with more than 95% of the buried dopant atoms on lattice sites. For these optimum growth conditions, a model is derived explaining the ob served incorporation of the Ga atoms. (C) 1995 American Institute of P hysics.