Growth of nominally undoped p-type ZnO on Si by pulsed-laser deposition

We report on the growth of nominally undoped p-type ZnO films on Si(111) substrates by pulsed-laser deposition. Hall effect measurements show that the undoped ZnO films change from n-type to p-type material when the oxygen pressure changes from 6×10−5to3×10−4Torr during growth. Ti∕Au contacts produce ohmic behavior to n-type ZnO (∼1017cm−3), but leaky Schottky behavior to p-type ZnO (∼1018cm−3). Electrical and photoluminescence results indicate that native defects, such as oxygen and zinc vacancies, could play an important role in determining the conductivity of these nominally undoped ZnO films.