Electrical properties of the HfO₂/Al₂O₃ dielectrics stacked using single- and dual-temperature atomic-layer deposition processes on In_0.53Ga_0.47As

Abstract

For sequential stacking of an Al 2 O 3 passivation layer and a main HfO 2 gate dielectric layer on In 0.53 Ga 0.47 As, we used single-and dual-temperature atomic-layer deposition processes, and systematically compared their effects on the dielectric-related electrical properties. When the deposition of Al 2 O 3 passivation layer (approximately 0.7−0.8 nm) took place at relatively low temperatures of 100 °C, an increase in the subsequent deposition temperature for HfO 2 (from 100 to 300 °C) assisted in decreasing both capacitance-equivalent oxide thickness and the number of bulk-related traps. However, the valuable reduction in both near-interface defect density and leakage current through the low-temperature Al 2 O 3 passivation approach was monotonically lessened with an increase in the process temperature for the subsequent HfO 2 deposition, which suggests the need for a careful optimization of a thermal budget for the dualtemperature process. Keywords: HfO 2 , Al 2 O 3 , In 0.53 Ga 0.47 As, atomic-layer deposition, dual-temperature process

Performance Enhancement and Bending Restoration for Flexible Amorphous Indium Gallium Zinc Oxide Thin-Film Transistors by Low-Temperature Supercritical Dehydration Treatment

“…The anomalous hump phenomenon is attributed to the existence of both the main current path composed of electrons and the parasitic current path induced by positive charges formed by redundant H 2 O molecules. , Therefore, after the CaCl 2 dehydration in the treatment system, the device drivability is enhanced and the hump phenomenon disappears. The hump effect also has a relationship with the quality of the dielectric layer, which is modified by the posttreatment and will be discussed in a later section.…”

“…We divide the I ds – V ds curves in Figure a into four regions: I ( V gs low, V ds low), II ( V gs low, V ds high), III ( V gs high, V ds low), and IV ( V gs high, V ds high) (Figure c) to analyze the charge trapping behavior. The diagrams of the energy band and interfacial trap density ( D it ) (Figure d,e) at the interface of a-IGZO/Al 2 O 3 , calculated using eq , can be used to understand this phenomenon where e is Eulter’s number, k is the Boltzmann constant, T is the absolute temperature, q is the unit electron charge, and C ox is the gate dielectric capacitance per unit area. By calculation, D it of the device before the treatment is 4.91 × 10 12 eV –1 cm –2 , which is more than twice that of the posttreatment device ( D it = 2.33 × 10 12 eV –1 cm –2 ).…”

“…During the treatment, a similar repair process occurs to the Al 2 O 3 gate dielectric layer as it does to the a-IGZO channel, and the traps around Al are restored to form Al–O bonds by the SCCO 2 fluid because of its strong penetration and superior oxidation capacity. After modification, the traps and dangling bonds on the interface induced by the sputtering a-IGZO process are reduced or disappear, so the hump effect of the original a-IGZO devices is eliminated Figure a shows that the percentage of nonlattice oxygen ((532.56 eV)) for the posttreated Al 2 O 3 is 17.3%, which is lower than that of the as-fabricated Al 2 O 3 (18.1%).…”

“…35,36 Therefore, after the CaCl 2 dehydration in the treatment system, the device drivability is enhanced and the hump phenomenon disappears. The hump effect also has a relationship with the quality of the dielectric layer, 37 which is modified by the posttreatment and will be discussed in a later section.…”

“…We divide the I ds −V ds curves in Figure 4a into four regions: I (V gs low, V ds low), II (V gs low, V ds high), III (V gs high, V ds low), and IV (V gs high, V ds high) (Figure 4c) to analyze the charge trapping behavior. The diagrams of the energy band and interfacial trap density (D it ) (Figure 4d,e) at the interface of a-IGZO/Al 2 O 3 , calculated using eq 2, 37 can be used to understand this phenomenon…”