B-N Codoped p Type ZnO Thin Films for Optoelectronic Applications
The success of codoping by donor-acceptor impurities in accomplishing p type ZnO thin films deposited by spray pyrolysis technique is reported here. Monodoping ZnO with N altered the conductivity type but the resistivity is too high making it practically impossible to be useful in optoelectronic applications. B-N codoping increased the carrier concentration and obtained comparatively low resistivity because codoping enhanced the acceptor incorporation by forming acceptor-donor-acceptor complex in the band gap. XRD analysis revealed the dependence of dopant incorporation on the texture and microstructure of the films. XPS analysis confirmed the enhancement of N incorporation with codoping. Energy gap value increased for codoped films due to the Burstein-Moss effect, arising from the increase in carrier concentration. Hence the present work envisages the preparation of transparent p type ZnO thin films suitable for tandem thin film solar cells and also for other optoelectronic applications.