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Atomic-layer-deposited Al2O3 and HfO2 on GaN: A comparative study on interfaces and electrical characteristics |
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| Authors: | Y.C. ChangM.L. Huang Y.H. ChangY.J. Lee H.C. ChiuJ. Kwo M. Hong |
| Affiliation: | a Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu 30013, Taiwan b Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan c Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan |
| Abstract: | Al2O3, HfO2, and composite HfO2/Al2O3 films were deposited on n-type GaN using atomic layer deposition (ALD). The interfacial layer of GaON and HfON was observed between HfO2 and GaN, whereas the absence of an interfacial layer at Al2O3/GaN was confirmed using X-ray photoelectron spectroscopy and transmission electron microscopy. The dielectric constants of Al2O3, HfO2, and composite HfO2/Al2O3 calculated from the C-V measurement are 9, 16.5, and 13.8, respectively. The Al2O3 employed as a template in the composite structure has suppressed the interfacial layer formation during the subsequent ALD-HfO2 and effectively reduced the gate leakage current. While the dielectric constant of the composite HfO2/Al2O3 film is lower than that of HfO2, the composite structure provides sharp oxide/GaN interface without interfacial layer, leading to better electrical properties. |
| Keywords: | MOS Atomic-layer-deposition (ALD) HfO2 Al2O3 GaN High k dielectric |
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