p-type ZnO thin films have been realized by a N-Al codoping method. The influence of homo-buffer layer oil film properties was studied in this work. The buffer layer was deposited at a high temperature of 600degreesC, and the desired codoped film was successively formed at 500degreesC on the first template layer. The N-Al codoped ZnO film was improved evidently in its crystal quality, optical quality and p-type conduction by adopting a homo-buffer layer. Hall measurements revealed that the p-type film had a low resistivity around 8.20Omegacm. The decrease in resistivity comes from a large increase of mobility (from 0.43 to 2.06 cm(2) V-1 s) and a slight increase of carrier concentration (typically about 10(17)cm(-3)). Introduction of a homo-buffer layer is a promising approach to realize p-type ZnO. (C) 2004 Elsevier B.V. All rights reserved.