Pulsed laser deposition of Zr–N codoped p -type ZnO thin films

Present p -type ZnO films tend to exhibit high resistivity and low carrier concentration, and they revert to their natural n-type state within days after deposition. One approach to grow higher quality p -type ZnO is by codoping the ZnO during growth. This article describes recent results from the growth and characterization of Zr–N codoped p -type ZnO thin films by pulsed laser deposition (PLD) on (0001) sapphire substrates. For this work, both N-doped and Zr–N codoped p -type ZnO films were grown for comparison purposes at substrate temperatures ranging between 400 to 700 °C and N 2 O background pressures between 10 −5 to 10 −2 Torr. The carrier type and conduction were found to be very sensitive to substrate temperature and N 2 O deposition pressure. P -type conduction was observed for films grown at pressures between 10 −3 to 10 −2 Torr. The Zr–N codoped ZnO films grown at 550 °C in 1×10 −3 Torr of N 2 O show p -type conduction behavior with a very low resistivity of 0.89 Ω-cm, a carrier concentration of 5.0×10 18 cm −3 , and a Hall mobility of 1.4 cm 2 V −1 s −1 . The structure, morphology and optical properties were also evaluated for both N-doped and Zr–N codoped ZnO films.