Atomic Nature of the Growth Mechanism of Atomic Layer Deposited High-κ Y2O3 on GaAs(001)-4 × 6 Based on in Situ Synchrotron Radiation Photoelectron Spectroscopy

Chiu-Ping Cheng; Wan-Sin Chen; Yi-Ting Cheng; Hsien-Wen Wan; Cheng-Yeh Yang; Tun-Wen Pi; Jueinai Kwo; Minghwei Hong

doi:10.1021/acsomega.7b01564

Atomic Nature of the Growth Mechanism of Atomic Layer Deposited High-κ Y₂O₃ on GaAs(001)-4 × 6 Based on in Situ Synchrotron Radiation Photoelectron Spectroscopy

ACS Omega. 2018 Feb 21;3(2):2111-2118. doi: 10.1021/acsomega.7b01564. eCollection 2018 Feb 28.

Authors

Chiu-Ping Cheng¹, Wan-Sin Chen², Yi-Ting Cheng², Hsien-Wen Wan², Cheng-Yeh Yang³, Tun-Wen Pi⁴, Jueinai Kwo³, Minghwei Hong²

Affiliations

¹ Department of Electrophysics, National Chiayi University, Chiayi 60004, Taiwan, ROC.
² Graduate Institute of Applied Physics and Department of Physics, National Taiwan University, Taipei 10617, Taiwan, ROC.
³ Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan, ROC.
⁴ National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan, ROC.

Abstract

Y₂O₃ was in situ deposited on a freshly grown molecular beam epitaxy GaAs(001)-4 × 6 surface by atomic layer deposition (ALD). In situ synchrotron radiation photoemission was used to study the mechanism of the tris(ethylcyclopentadienyl)yttrium [Y(CpEt)₃] and H₂O process. The exponential attenuation of Ga 3d photoelectrons confirmed the laminar growth of ALD-Y₂O₃. In the embryo stage of the first ALD half-cycle with only Y(CpEt)₃, the precursors reside on the faulted As atoms and undergo a charge transfer to the bonded As atoms. The subsequent ALD half-cycle of H₂O molecules removes the bonded As atoms, and the oxygen atoms bond with the underneath Ga atoms. The product of a line of Ga-O-Y bonds stabilizes the Y₂O₃ films on the GaAs substrate. The resulting coordinatively unsaturated Y-O pairs of Y₂O₃ open the next ALD series. The absence of Ga₂O₃, As₂O₃, and As₂O₅ states may play an important role in the attainment of low interfacial trap densities (D _it) of <10¹² cm^-2 eV^-1 in our established reports.