Table 4: XRD ω-scan width of ZnO (0002) peak, PL-D0XA FWHM, Hall mobility μ H, and carrier concentration n of a series of ZnO thin films grown by the indicated multi-step PLD process on c-plane sapphire substrate. The nucleation and intermediate layers are always 30 nm, and the main layers are 1,200 nm thick. The thin nucleation and interlayers are grown at 600°C and the thick ZnO layers at 1 . 5 × 1 0 2  mbar oxygen partial pressure and 750°C growth temperature [102].

PLD stepsXRD ω-scan ZnO(002) (arsec)FWHM PL-D0XA (2 K) (meV)μ H(cm2/Vs) (300 K) 𝑛 (cm-3) (300 K)

One-step4463.230 5 × 1 0 1 7
Two-step high temp.*3202.460 1 . 4 × 1 0 1 6
Two-step3382.2141 5 . 4 × 1 0 1 6
Three-step2412.0119 2 . 8 × 1 0 1 6
Four-step2561.9101 7 . 5 × 1 0 1 5

*750°C growth temperature for the thin nucleation layer, instead of 600°C at the other processes.