MISORIENTATION DEPENDENCE OF ZINC INCORPORATION IN GAAS

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 [01BAR1] 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 4-degrees 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 kinksites at higher misorientation angles.