The Effects of an O2 Plasma on the Optical Properties of Atomic Layer Deposited ZnO

Abstract

The optical properties of atomic layer deposited (ALD) ZnO thin films were explored in detail. A plasma enhanced-ALD process using diethlyzinc and a remote O2 plasma as well as a plasma enhanced thermal-ALD method in which a remote O2 plasma step is added after each cycle of the classic thermal-ALD process were investigated. The optical properties of the films were found to depend strongly on the ALD process and plasma conditions. Absorption and room temperature photoluminescence (PL) measurements indicate both the bandgap and defect concentrations in the ZnO films are affected by the plasma. The low temperature PL characteristics of the films are also affected by the plasma, providing further evidence that it has distinct effects on the growth process and in turn ZnO material properties.