Effect of Precursor-Pulse on Properties of Al-Doped ZnO Films Grown by Atomic Layer Deposition

摘要

Al-doped ZnO (ZnO:Al) films were grown by repeated sequential precursor reaction cycles (diethylzinc, Zn(C_2H_5)_2; Ar purge; H_2O; Ar purge; trimethylaluminum, Al(CH_3)_3) with a given pulse ratio of trimethylaluminum (TMA) to diethylzinc (DEZ). As the cycle ratio of TMA to DEZ (TMA/DEZ) increased, the resistivity of the films decreased and the roughness increased. For a TMA/DEZ pulse ratio of 1 to 10, the film had a resistivity of 9.7 x 10~(-4) Ω·cm and a roughness of 2.25 nm (rms), while for only DEZ injection, the film had a resistivity of 3.5 x 10~(-3) Ω·cm and a roughness of 1.07nm (rms). The transmittance of the films was in excess of 80% for all samples with individually better performances corresponding to their respective wavelength ranges. For a successful atomic layer-controlled reaction, in order to avoid a pyrolytic gas-phase reaction, Ar purge time between the introduction of precursors is a key factor. For our reaction chamber, the purge time should be longer than 15 s and the corresponding growth rate is 2.2 A/cycle.