Study on Phase Transition of Zn1-XMgXO Thin Films Grown by MOCVD Process

We have grown Zn_1-xMg_xO films by MOCVD process with a gas mixture of diethylzinc(DEZ), H₂O and bis-methylcyclopentadienyl-Mg {MeCp₂Mg:(CH₃C₅ H₄Mg)}. We found that phase transition from wurtzite to rocksalt structure was strongly influenced by substrate temperature and MeCp₂Mg gas phase concentration. Wurtzite structure was dominant under high substrate temperature, and rocksalt was dominant under high MeCp₂Mg gas phase concentration. This behavior was in good agreement with our calculation of enthalpy for each structure. We also found that film structure was not uniform in growth direction under low substrate temperature due to the phase transition. These result suggested that higher growth temperature were preferable to the growth of high Mg content wurtzite Zn_1-xMg_xO for the MOCVD process