TY - JOUR
T1 - Electronic structure and origin of intrinsic defects in sputtered HfTiO2 alloy dielectric on GaAs surface
AU - Mahata, Chandreswar
AU - Jyothirmai, Mullapudi V.
AU - Ravva, Mahesh Kumar
AU - Chakrabortty, Sabyasachi
AU - Kim, Sungjun
AU - Biring, Sajal
AU - Ramakrishna, Seeram
AU - Dalapati, Goutam Kumar
N1 - Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/7/25
Y1 - 2022/7/25
N2 - 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.
AB - 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.
KW - Arsenic-dangling bond passivation
KW - Density-functional theory
KW - GaAs-high-k
KW - HfTiO alloy
KW - Intrinsic defects
UR - http://www.scopus.com/inward/record.url?scp=85129391048&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2022.164817
DO - 10.1016/j.jallcom.2022.164817
M3 - Article
AN - SCOPUS:85129391048
SN - 0925-8388
VL - 910
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 164817
ER -