Effects of interfacial sulfidization and thermal annealing on the electrical properties of an atomic-layer-deposited Al2O3 gate dielectric on GaAs substrate

Abstract

In this study we investigated the interfacial chemistry occurring between an atomic-layer-deposited Al2O3 high-k film and a GaAs substrate and the impact of sulfidization and thermal annealing on the properties of the resultant capacitor. We observed that sulfide passivation of the Al2O3∕GaAs structure improved the effect of Fermi level pinning on the electrical characteristics, thereby providing a higher oxide capacitance, smaller frequency dispersion, and reduced surface states, as well as decreased interfacial charge trapping and gate leakage currents. Photoemission analysis indicated that the (NH4)2S-treated GaAs improved the quality of the as-deposited Al2O3 thin film and preserved the stoichiometry of the dielectric during subsequent high-temperature annealing. This behavior was closely correlated to the diminution of GaAs native oxides and elemental arsenic defects and their unwanted diffusion. In addition, thermal processing under an O2 atmosphere, relative to that under N2, decreased the thickness of the Al2O3 gate dielectric and relieved the gate leakage degradation induced by metallic arsenic; as a result, superior dielectric reliability was attained. We discuss the underlying thermochemical reactions that account for these experimental observations.

Comparison of the reactivity of alkyl and alkyl amine precursors with native oxide GaAs(100) and InAs(100) surfaces

“…Select samples were subjected to a PDA treatment at 600°C for 1 min in an argon atmosphere using an ULVAC MILA annealer. These parameters were typical for PDA treatments used in related works [18,21,32,33].…”

Effect of pulsed deposition of Al2O3 for native oxides reduction of GaAs by atomic layer deposition technique

“…Quantitatively, the relative decrease in the As-O intensity is 44, 65, 68, and 79 % for NH 4 OH cleaned, 2, 4, and 6 s of TMA, respectively, and no thermal conversion of mixed Ga/As oxides was observed. 3,13,17 The current results suggest that the thermal conversion of mixed Ga/As oxides can be avoided significantly at temperature 280 C. It is believed that the consumption of oxides proceeds via ligand exchange reaction between the metal precursor and native oxides. 17 Although the exact fundamental mechanism of ALD is yet to be known, the following possible reaction is given as an example.…”

“…1 Compound semiconductors such as GaAs and other III-V materials have the potential to replace Si as the channel material in metal-oxide-semiconductor-field-effect-transistors (MOSFETs) due to their high electron mobility. [2][3][4][5] However, the poor gate oxide/III-V interface quality has hindered fabrication of high-performance III-V channel MOSFETs. Among III-V semiconductors, GaAs and InGaAs are promising substrate materials for high-k dielectric deposition, 6,7 although cleaning of GaAs surface is a key issue for epitaxial layers growth.…”

Impact of the Al/Hf ratio on the electrical properties and band alignments of atomic-layer-deposited HfO2/Al2O3on S-passivated GaAs substrates

“…The Ga 2p3/2 and As 2p3/2 spectra for HfO 2 , Al 2 O 3 and AHO thin films deposited on GaAs are shown in figure 2. The Ga native oxides of the GaAs surface consists of Ga 3+ , Ga 5+ and Ga suboxides, and the As native oxide of the GaAs surface has mainly As 3+ and As 5+ oxidation states [13,15]. After HCland (NH 4 ) 2 S-treatments, the GaAs surface was also detected by XPS (not shown here).…”

“…Besides the barrier height, the interface quality is also an important factor affecting the leakage characteristics. The appearance of the elemental As overlayer or As oxides can result in the formation of the traps at the dielectric/GaAs interface, causing the increase of J A subsequently [15]. The Al 2 O 3 /GaAs structure after PDA in N 2 does not show better leakage properties though it possesses the largest barrier heights.…”