POSTPONED: Revolution In P-type Oxide Semiconductor Development Toward Next Generation Flexible Electronics


Jacobs Hall, Room 4309, Jacobs School of Engineering, 9500 Gilman Dr, La Jolla, San Diego, California 92093

Sponsored By:
Prof. Yuhwa Lo

Kenji Nomura, Ph.D.
Kenji Nomura, Ph.D.



Metal oxide semiconductor device technology is to date widely accepted as a technology that enable the development of next generation device applications such as flexible, transparent and low cost electronic devices because of its superior material property such as reasonably high electron mobility (>10cm2(Vs)-1) and wide compatibility of processing including solution process. However, oxides with excellent electrical property are all n-type represented by ZnO and a-In-Ga-Zn-O due to the electronic structures composed of a conduction band minimum (CBM) and valence band maximum (VBM) with different characteristics. The absence of high performance p-type oxide limits the device application and is largest drawback in oxide device technology. Therefore, next challenge is to develop high performance p-type oxide to realize p-channel TFT and complimentary circuit, and pn-juntion devices such as photovoltaic and light-emitting devices. To achieve this, it is imperative to choose not only a material exhibiting good hole transport but also to clarify impurity effect and in-gap defect structure and to develop an effective defect termination method. Here I will present the development of high performance p-type oxide for TFT application and the complimentary inverter circuit composed of p/n-type oxides. Firstly, I will explain why the hole transport in oxide is so difficult and how we select p-type candidates. Then I will show how to terminate in-gap defect for improving the device characteristics. Finally, I would like to discuss the material design for amorphous p-type oxide.

Speaker Bio:
Kenji Nomura is principle engineer at Qualcomm Inc. He received the B.E. degree in Applied chemistry and the M.E. degree in Material science engineering from the Nagoya Institute of Technology, Japan, in 1999, and 2001, respectively, and the Ph.D. degrees in Material science engineering from the Tokyo Institute of Technology (Tokyo Tech.), Japan, in 2004. After that, he joined the Material science laboratory, Tokyo Tech., as a post-doctoral researcher, and in 2010 became an Associate Professor in Frontier research center. He developed several key oxide semiconductor materials for TFT application and invented high performance oxide-TFTs. Since June 2012, he joined Qualcomm Inc., He has been working on oxide electronic material development projects. His current research interests include oxide electronics and flexible electronics, in particular oxide semiconductor device application such as TFT, LED and sensing devices. He has 115 academic journal papers on oxide material science and semiconductor device physics.

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