In-situ doping during ZnO atomic layer deposition

Abstract

We have deposited transparent conducting Al-doped ZnO films on glass and Si substrates by atomic layer deposition (ALD) at a relatively low substrate temperature of 200 degrees C and evaluated the electrical and the optical properties of these films. For Al-doped ZnO film growth by using the ALD process, diethylzinc (DEZ) and trimethylaluminum (TMA) were used as metal precursors and water as a reactant. The process conditions were optimized by varying the deposition temperature, The TMA:DEZ cycle ratio and TMA exposure time and an Al-doped ZnO film with a resistivity of 1.09 x 10(-3) Omega.cm, a carrier concentration of 1.16 x 10(21) cm(-3) and a carrier mobility of 5.0 cm(2)/V.S was attained. In addition, the Al-doped ZnO film was focused to have a relevant transmittance as a transparent conducting electrode. The transmittances of the film in the visible region were in excess of 80% (450 nm <= lambda <= 1100 nm) and 65% (380 nm <= lambda <= 450 nm).