Transparent and conductive undoped zinc oxide thin films grown by atomic layer deposition

Atomic layer deposition (ALD) was used to fabricate transparent and conductive thin films of ZnO. Two hundred-nano metre thick ZnO films were deposited on glass substrates at low growth temperatures varied between 120 and 240 degrees C. As zinc and oxygen precursors we used diethylzinc (DEZn) and deionized water, respectively. To find optimal film parameters, the structure, surface morphology, optical and electrical measurements were carried on. The films obtained at 200 degrees C show the highest carrier concentration (similar to 10(20)cm(-3)) and the lowest resistivity (2 x 10(-3) Omega cm). The films exhibit mobilities up to 37 cm(2)/Vs that we associate to the process technology used. An important point of our approach was that the films studied were not intentionally doped (with Al or other group III elements) but the high electrical conductivity was achieved by playing with the sample stoichiometry and growth conditions. (C) 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim