N-type transparent conducting oxides are based on ionic oxides with s-like cation conduction bands. The effect of disorder on their conduction band states is found to be small, because angular disorder has no effect on s states. Aliovalent impurities give rise to shallow states at the conduction band, which leads to an absence of a conduction band tail of localized states. This leads to a higher electron mobility than in typical p state amorphous materials like a-Si, the ability to move the Fermi level well into the conduction band and an absence of electrical instability as in a-Si:H. The band offsets. are used to suggest appropriate oxide dielectrics for their thin transistors. (c) 2007 Elsevier B.V. All rights reserved.