Doping studies of zinc have been carried out for metalorganic chemical vapour deposition (MOCVD) grown GaAs, with diethyl zinc as precursor. The zinc incorporation has been studied as a function of the zinc input mole fraction, growth temperature and substrate misorientation. It is found that the zinc incorporation on (001) substrates misoriented towards [011] and [011] directions showed a consistent and similar dependence on the misorientation angle at various zinc input mole fractions, with an observed minimum in the Zn-incorporation at 40 off. The observed temperature dependence leads to a apparent activation energy of -59 kcal/mol for zinc incorporation which is attributed to the enthalpy involved in the formation of two bonds during the incorporation. The dependence on the misorientation angle is explained by competition between the influence of "step trapping" at lower misorientation (and higher step velocities) and the increase of available kinksitcs at higher misorientation angles. _______ and trimethyl gallium (TMG) as growth precur-0 Corresponding author SOFS, and hydrogen, purified by a Pd-diffusion 0022-0248/94/$07.OO

Doping studies of the incorporation behaviour of three different dopants (Zn, In and Si) versus the misorientation of the (100) surface during MOVPE growth of GaAs have been carried out with diethylzinc, trimethylindium and disilane as precursors. The incorporation of the dopants has been studied as function of the input mole fraction dopant, growth temperature, degree and direction of misorientation. In order to explain the results we discuss the BCF theory and the nature of the steps as function of above mentioned parameters. It appears that the BCF theory alone cannot explain the results, a counteracting mechanism has been introduced based on preferential arsenic desorption from the step edges.

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