AVS 59th Annual International Symposium and Exhibition
    Transparent Conductors and Printable Electronics Focus Topic Thursday Sessions
       Session TC+EM+AS+TF+EN-ThM

Invited Paper TC+EM+AS+TF+EN-ThM3
Recent Progress in Oxide Semiconductors and Oxide TFTs

Thursday, November 1, 2012, 8:40 am, Room 007

Session: Transparent Conductors and Devices
Presenter: H. Hosono, Tokyo Institute of Technology, Japan
Correspondent: Click to Email

Transparent conductive oxides (TCOs) andtransparent oxide semiconductors (TOSs) have a long history since 1950s. Thematerial design concept for TCOs looks almost established, i.e., ionic oxidesp-block metals with an electronic configuration of (n-1)d10ns0and a spatial spread of ns orbitals which is enough to have large overlap withneighboring metal ns orbitals irrespective of intervening oxygen ion1).Concretely, most of the TCOs have been realized in the material systems of In2O3-SnO2-CdO-Ga2O3-ZnO. Materials based on light metal oxides such asAl2O3 and SiO2 have not been regarded as thecandidates of TCOs. In 2002, we2) reported high electronicconductivity in 12CaO·7Al2O3(C12A7) which had been a typicalinsulator and this discovery was followed by transparent conductivity in cubicSrGeO3 in 2011.3) These two materials are TCOs realized by a newmaterial design concept.

Asfor TOS, the striking advances are seen in transparent amorphous oxide semiconductors(TAOS) in science and technology due to strong demand for active layermaterials in thin film transistors (TFTs). Amorphous In-Ga-Zn-O (IGZO) TFTs,which was first reported in late 2004,4) has adopted to drive highresolution displays of new iPad.5) This is a first mass productionof TOS family. The major reasons forthis adoption are high electron mobility (an order of larger than that ofa-Si:H) and easy fabrication process. Amajor advance in TOS-TFTs is realization of p-channel TFTs and subsequentfabrication of C-MOS using ambipolar SnO. 6)

Inthis talk, I review these progresses viewed from electronic state of thesematerials.

1) H.Kawazoe,H.Yanagi,K.Ueda, and H.Hosono. MRS Bull,25,28(2000)

2) K.Hayashi, S.Msuishi, T.Kamiya,M.Hirano, H.Hosono, Nature 419, 462 (2002).

3) H.Mizoguchi,T.Kamiya, S.Matsuishi, H.Hosono: Nat.Commun., 2, 470 (2011).

4) K.Nomura,H.Ohta, A.Takagi, T. Kamiya, M. Hirano, H.Hosono,Nature 432, 488 (2004).

5) Sharp Press Release April 6, 2012

6) K.Nomura,T.Kamiya , and H. Hosono: Adv. Mater., 23, 3431 (2011)