Effects of Mg content and B doping on structural, electrical and optical properties of Zn1−xMgxO thin films prepared by MOCVD

Zn1−xMgxO (ZMO) thin films have been successfully prepared using metal organic chemical vapor deposition (MOCVD). The structural, electrical and optical properties of ZMO thin films deposited under a series of conditions have been investigated. X-ray diffraction (XRD) studies indicate that the ZMO and ZMO:B films in this work are of the hexagonal wurtzite ZnO structure with (1 0 1) plane preferential growth. The growth rate of ZMO films increases gradually with an increase of Mg flow rate during the deposition. In addition, the B2H6 flow rate can influence the interplanar distance and the grain size of the ZMO:B films. By varying the B doping concentration, the resistivity of a ZMO:B thin film can be reduced to about 10−5 Ω cm. The optical measurements reveal a blue shift of the absorption edge, a high transmittance of about 90% in visible regions and a high absorption of about 100% in UV regions. Tuning of the band gap energy is obtained from 3.32 to 3.74 eV for ZMO films and 3.58 to 3.88 eV for ZMO:B films, which demonstrates that these films have potential application in UV detectors and as the window layer of thin film solar cells.