P-Type Conduction in Sputtered ZnO Thin Films Doped by Nitrogen

Nitrogen doped zinc oxide (ZnO:N) thin films were prepared by RF diode sputtering from ZnO target in different ratio of Ar/N
₂
gas mixture. The p-type features of ZnO:N thin films have been caused by the incorporation of the nitrogen acceptor NO into ZnO what was proven by second ion mass spectroscopy (SIMS) analysis. The minimum value of resistivity of 790 Omegacm, a Hall mobility of 22 cm
²
V
^-1
s
^-1
and the carrier concentration of 3.6 times 10
¹⁴
cm
^-3
were yielded at 75 % N
₂
. X-ray diffraction measurements (XRD) showed that ZnO:N films had the preferential orientation of (002) plane at 25 % N
₂
and of (100) plane for higher N
₂
concentrations. The average grain size was from 7 to 42 nm for all Ar/N
₂
ratios. ZnO:N films exhibit relatively high micro strains (10 times 10
^-3
)