Articles
  • Measurement of band offsets in MgO/InGaZnO4 heterojunction by X-ray photoelectron spectroscopy
  • B.S. Choia, K. W. Kimb, B. P Gilab, D. P. Nortonb, S. J. Peartonb and Hyun Choc,*
  • a Department of Nano Fusion Technology, Pusan National University, Gyeongnam 50463, Korea b Department of Materials Science and Engineering, University of Florida, Gainesville, FL 32611, USA c Department of Nanomechatronics Engineering, Pusan National University, Busan 46241, Korea
Abstract
Amorphous InGaZnO4 (α-IGZO) thin film transistors (TFTs) are one of the most promising candidates for switches in the active-matrix and driver-integrated circuits of transparent liquid crystal displays and flexible displays. The stability and overall performance of amorphous IGZO TFTs depend to a great extent on the band offsets in gate dielectric/α-IGZO heterojunction. The energy discontinuity in the valence band (ΔEV) and conduction band (ΔEC) in MgO/IGZO heterojunctions were systematically examined by using X-ray photoelectron spectroscopy (XPS). The MgO gate dielectric was found to have a straddled type band offset alignment on the IGZO. The valence band offset value for the MgO/IGZO heterojunction was determined as 0.81 ± 0.17 eV using the Ga 2p3/2, Zn 2p3/2 and In 3d5/2 energy levels as references. The bandgap energy difference between the MgO and IGZO led to a corresponding conduction band offset (ΔEC) of ~3.79 eV and a nested interface alignment

Keywords: MgO/InGaZnO4 heterojunction, Band offsets, XPS, Interface alignment

This Article

  • 2017; 18(9): 687-690

    Published on Sep 30, 2017