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

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...

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Published in:Journal of alloys and compounds 2022-07, Vol.910, p.164817, Article 164817
Main Authors: Mahata, Chandreswar, Jyothirmai, Mullapudi V., Ravva, Mahesh Kumar, Chakrabortty, Sabyasachi, Kim, Sungjun, Biring, Sajal, Ramakrishna, Seeram, Dalapati, Goutam Kumar
Format: Article
Language:English
Subjects:
Amorphous alloys
Arsenic-dangling bond passivation
Chemical bonds
Density functional theory
Deposition
Electrical properties
Electronic structure
GaAs-high-k
Gallium arsenide
Hafnium oxide
HfTiO2 alloy
Intrinsic defects
Mathematical analysis
Photoelectrons
Substrates
Surface reactions
Thin films
Titanium dioxide
X ray photoelectron spectroscopy
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Summary: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. •Electronic structure at the atomistic level of single and alloy dielectric/GaAs interface investigated.•Co-sputtered amorphous-HfTiO2 alloy dielectric reduces interface As-related dangling bonds.•Interface structure and surface reaction analyzed by HRTEM and Angle-resolved XPS.•density-functional theory (DFT) calculations for the bandgap and valence band offset of high-k/GaAs interface•Ti-atoms bridging between the As-dangling bonds studied and analyzed by ARXPS and electrical characterizations.
ISSN:0925-8388
1873-4669
DOI:10.1016/j.jallcom.2022.164817