Local p-type conduction of Na-doped ZnO thin films grown by MOCVD

Growth of Na-doped ZnO thin films by low-pressure metal–organic chemical vapor deposition method was realized using cyclopentadienylsodium as the sodium source. Secondary ion mass spectrometry measurements revealed the existence of Na in the ZnO thin films. Low-temperature scanning tunneling microscopy and scanning tunneling spectroscopy were used for obtaining local density of states (LDOS) of the Na-doped ZnO thin films at nanometer scale. The local measurements indicated a spatial distribution of the LDOS as well as the conductivity type that could be linked to spatial variations of Na doping level.