Electronic structure and origin of intrinsic defects in sputtered HfTiO2 alloy dielectric on GaAs surface

Chandreswar Mahata, Mullapudi V. Jyothirmai, Mahesh Kumar Ravva, Sabyasachi Chakrabortty, Sungjun Kim, Sajal Biring, Seeram Ramakrishna, Goutam Kumar Dalapati

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3 Scopus citations

Abstract

In this work, we have investigated the electronic structure and electrical properties of sputter-deposited high-k dielectrics grown on p-GaAs substrate with post-deposition annealing at 500 °C/N2 ambient. Capacitance-voltage results show that co-sputtered amorphous-HfTiO2 alloy dielectric can reduce interfacial dangling bonds. HRTEM and AR- X-ray photoelectron spectroscopy results confirmed the formation of a thin interfacial layer during sputter deposition. At the atomistic level, the surface reaction and electronic interface structure were investigated by density-functional theory (DFT) calculations. Using the HSE functional, theoretical calculations of bulk HfO2, a-TiO2, and HfTiO2 band gaps are found to be 5.27, 2.61, and 4.03 eV, respectively. Consequently, in the HfTiO2/GaAs interface, the valance band offset is found to be reduced to 1.04 eV compared to HfO2/GaAs structure valance band offset of 1.45 eV. Reduction in border trap density (~1011 V/cm2) was observed due to Ti atoms bridging between As-dangling bonds. The angle-resolved XPS analysis further confirmed Ti-O-As chemical bonding with very thin (~20 Å) dielectric layers.

Original languageEnglish
Article number164817
JournalJournal of Alloys and Compounds
Volume910
DOIs
StatePublished - 25 Jul 2022

Keywords

  • Arsenic-dangling bond passivation
  • Density-functional theory
  • GaAs-high-k
  • HfTiO alloy
  • Intrinsic defects

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