Oxide Thin Film Heterostructures on Large Area, with Flexible Doping, Low Dislocation Density, and Abrupt Interfaces: Grown by Pulsed Laser Deposition

Table 4

XRD ω-scan width of ZnO (0002) peak, PL-D⁰X_A 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 1.5×10⁻² mbar oxygen partial pressure and 750°C growth temperature [102].

PLD steps	XRD ω-scan ZnO(002) (arsec)	FWHM PL-D^0XA (2 K) (meV)	μ H(cm^2/Vs) (300 K)	𝑛 (cm^-3) (300 K)
One-step	446	3.2	30	5×10^17
Two-step high temp.*	320	2.4	60	1.4×10^16
Two-step	338	2.2	141	5.4×10^16
Three-step	241	2.0	119	2.8×10^16
Four-step	256	1.9	101	7.5×10^15

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