Gas-phase reaction mechanism of p-type doping in group III nitrides growth: auxiliary decomposition effect of H radicals on Cp2Mg

In this study, the reaction mechanism of p-type dopant Cp2Mg in the gas phase of MOCVD was proposed and analyzed by quantum chemical calculations in accordance with density functional theory. The possibility of each reaction proceeding at various temperatures was determined, respectively. It was reported that Cp2Mg primarily displayed two competing paths of addition and hydrogenolysis. For adduct reaction path, complex Cp2Mg:NH3 or Cp2Mg:(NH3)2 would be formed in the temperature range below 420 K. For the hydrogenolysis pathway, the H radical in the gas phase was a “double-edged sword.” On the one hand, H radical exerted a positive auxiliary effect on Cp2Mg decomposition, significantly lowering the decomposition temperature of Cp2Mg. On the other hand, H radical reacted with Mg to form Mg–H gas-phase complex, passivating Mg and hindering the effect of p-type doping.