Interfacial Electrical Properties of HfO2/Al2O3/GaSb MOS Capacitors Prepared by Atomic Layer Deposition
| Autor: | Hsien-Ming Hsu, 徐賢名 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 According to Moor’s law, the density of transistors on a single integrated circuit chip doubles every 18 months. However, the gain in cost and performance is not commensurate with simple dimension scaling anymore because Si-based transistors are approaching their physical limit, especially in the sub-10 nm regime. This has prompted great interest in high mobility III-V compounds as alternatives of transistor channel materials. However, the native oxides of III-V compounds are complex in structure and composition. They form defects at the oxide-semiconductor interface and hinder the construction of ideal metal-oxide-semiconductor field-effect transistors. In this study, two methods are successfully used to suppress the defect state density of high-κ/GaSb interface as demonstrated in the metal-oxide-semiconductor capacitors (MOSCAPs). The HfO2/Al2O3 bi-layer oxide films used in this study are deposited on GaSb samples in an atomic layer deposition system that is connected to a molecular beam epitaxy system with ultra-high vacuum transfer chambers. With this tool, the as-grown GaSb can be transferred to the atomic layer deposition system for high-κ deposition with no or little surface native oxides. The MOSCAPs prepared by this method show effective capacitance modulation of 31 % with interface state density of 5.27×1012 eV-1cm-2 at 300 K. Hydrogen plasma treatment is another method proposed to clean the surface of GaSb before high-κ dielectric deposition. The native oxide on GaSb, which has been exposed to air, is effectively removed through the chemical reactions with hydrogen radicals. The MOSCAPs prepared by this method show effective capacitance modulation of 36 % with interface state density of 3.81×1012 eV-1cm-2. The result obtained in this work is encouraging toward the realization of GaSb MOSFETs with high on/off ratio and low sub-threshold swing. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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