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|Type of Document
||Characterization of III-V Compound Semiconductor MOSFETs with Titanium Oxide and Aluminum Oxide Stacked Layers as Gate Oxides|
|Date of Defense
III-V Compound Semiconductor
||Due to the high electron mobility compared with Si, much attention has been focused on III-V compound semiconductors (gallium arsenide (GaAs), indium phosphide (InP), indium gallium arsenide (InGaAs)) high-speed devices. The high-k material TiO2 not only has high dielectric constant (k =35-100) but also has well lattice match with GaAs, InP and InGaAs substrate. Therefore, titanium oxide (TiO2) was chosen to be the gate oxide in this study, and aluminum oxide (Al2O3) has high bandgap (Eg~9eV) and self-cleaning capability, we use TiO2 and Al2O3 stack layers to decrease leakage currents and increase capacitance.|
The major problem of III-V compound semiconductor is known to have poor native oxide on it leading to the Fermi level pinning at the interface of oxide and semiconductor. The C-V stretch-out phenomenon can be observed and the leakage current is high. Use atomic layer deposition (ALD) system to grow stack double layers ALD-TiO2 and ALD-Al2O3 films on III-V substrate by high-k of TiO2 and high bandgap and self-cleaning capability of Al2O3 to reduce only one layer’s defect.
The surface passivation of III-V with (NH4)2S treatment (S-III-V) could prevent it from oxidizing after cleaning and improve the interface properties of MOSFET. The leakage current of sulfur passivation can be improved. The leakage current densities are 7.31 x 10-7, 3.11 x 10-6 and 7.40 x 10-7 A/cm2 at ±2.0MV/cm, respectively. The (NH4)2S is necessary to passivation III-V surface form S-thin film of fabrication of III-V devices.
||Jeng Gong - chair|
Min-Yen Yeh - co-chair
Chin-Feng Yen - co-chair
Ming Kwei Lee - advisor
Ying-Chung Chen - advisor
Indicate in-campus at 99 year and off-campus access at 99 year.|
|Date of Submission