Enhanced incorporation of doped impurity in GaAs by alternate doping of Te and S is reported. When diethyltelluride (DETe) was injected on GaAs surface covered with S, the incorporation of Te was enhanced and it is shown that the Te concentration was increased according to the S coverage. Mechanism of enhanced impurity incorporation is discussed in view of the charge distribution in the molecules and the electronegativity difference. (C) 2002 Elsevier Science B.V. All rights reserved.