Papers Published

  1. Chen, C.H. and Gosele, U.M. and Tan, T.Y., Dopant diffusion and segregation in semiconductor heterostructures. Pt. 1. Zn and Be in III-V compound superlattices, Appl. Phys. A, Mater. Sci. Process. (Germany), vol. 68 no. 1 (1999), pp. 9 - 18 [s003390050847] .
    (last updated on 2007/04/10)

    Abstract:
    Distribution of shallow dopants in semiconductor heterostructures in general exhibits a pronounced segregation phenomenon, which requires the description of the dopant atom diffusion and segregation processes simultaneously. We treat this class of problems in a series of three papers. In the present paper, which is the first of the three, Zn and Be distributions in III-V superlattice (SL) structures are discussed in detail. The analysis method developed in this paper is generally applicable to other cases. In the second paper we analyze B distribution in GeSi/Si heterostructures. In the third paper we treat the problems associated with a number of n-type dopants in a variety of semiconductor heterostructures. Segregation of a dopant species between two semiconductor heterostructure layers is explained by a model incorporating (i) a chemical effect on the neutral species; and (ii) a Fermi-level effect on the ionized species, because, in addition to the chemical effect, the solubility of the species also has a dependence on the semiconductor Fermi-level position. For Zn and Be in GaAs and related compounds, their diffusion process is governed by the doubly-positively-charged group III element self-interstitials (IIII2+), whose thermal equilibrium concentration, and hence also the diffusivity of Zn and Be, exhibit also a Fermi-level dependence, i.e., in proportion to p2. A heterojunction consists of a space-charge region with an electric field, in which the hole concentration is different from those in the bulk of either of the two layers forming the junction

    Keywords:
    aluminium compounds;annealing;beryllium;diffusion;doping profiles;Fermi level;gallium arsenide;hole density;III-V semiconductors;impurity states;indium compounds;segregation;semiconductor heterojunctions;semiconductor superlattices;zinc;