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Oxidized Metal Schottky Contacts on (010) β-Ga2 O 3
摘要： Oxidized Ir, Pd, Pt, Ag, and Au Schottky contacts (SCs) were fabricated on (010) β-Ga2O3 single crystal substrates via reactive rf sputtering using an O2:Ar plasma. The use of in-situ oxidizing conditions resulted in SCs with very high rectifying barriers in excess of 2.0 eV for all the metals investigated, representing an increase of 0.4 to 0.9 eV compared to the corresponding plain metal versions. Both the plain and oxidized metal SCs showed evidence of Fermi Level pinning with their laterally homogeneous barrier heights lying in narrow ranges of ~1.3 to 1.5 eV and ~2.2 to 2.4 eV, respectively, with little correlation with metal work function. This was attributed to the influence of metal-induced oxygen vacancies and gap states at the SC interface, respectively. The very high barriers of the oxidized SCs resulted in excellent high temperature performance with ~10 orders of magnitude of rectification at 180 oC, indicating the potential of this technique for the fabrication of high temperature unipolar devices.
关键词： Metal Induced Gap States,Fermi Level Pinning,Oxygen Vacancies,Semiconductor Interfaces,Schottky Diodes
更新于2025-09-23 15:22:29
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Creation of Two-Dimensional Electron Gas and Role of Surface Donors in III-N Metal-Oxide-Semiconductor High-Electron Mobility Transistors
摘要： The role of surface donors at the oxide/semiconductor interface of III-N metal-oxide-semiconductor (MOS) high-electron mobility transistors (HEMTs), by creating a two-dimensional electron gas (2DEG) and the device performance, are investigated. Al2O3/GaN/AlGaN/GaN MOS HEMTs show the surface donor density (Nd,surf ) of 2.2 (cid:1) 1013 cm(cid:3)2 which is increased up to 3.4 (cid:1) 1013 cm(cid:3)2 after post-deposition annealing. In the latter, surface donors fully compensate the surface polarization charge and the HEMT threshold voltage decreases substantially with the oxide thickness. On the other hand, an open-channel drain current is found to be independent of Nd,surf, while marginal trapping is completely removed when Nd,surf increases with annealing. Consequently, ionized surface donors behave like a fixed charge and are clearly distinguishable from trapping states. Open-channel 2DEG densities of (cid:4)1.1 (cid:1) 1013 cm(cid:3)2 are extracted from capacitance–voltage measurements. Similarly, recent data on enhancement-mode HfO2/InAlN/AlN/GaN MOS HEMTs are analyzed where Nd,surf is reduced down to (cid:3)2 while 2DEG densities reach (cid:4)2.7 (cid:1) 1013 cm(cid:3)2. It is suggested that under the open-channel condition, 2DEG is supplied also by an injecting source contact if Nd,surf is lower than the QW polarization charge. Our charge quantifications are supported by calculating energy-band diagrams.
关键词： oxide-semiconductor interfaces,AlGaN/GaN high-electron mobility transistors (HEMTs),polarization
更新于2025-09-09 09:28:46
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[IEEE 2018 International Semiconductor Conference (CAS) - Sinaia, Romania (2018.10.10-2018.10.12)] 2018 International Semiconductor Conference (CAS) - Second Harmonic Generation: A Non-Destructive Characterization Method for Dielectric-Semiconductor Interfaces
摘要： This paper reviews the application of second harmonic generation (SHG) to characterize dielectric-semiconductor interfaces in microelectronics and photovoltaics. Based on non-linear optics, the method is non-destructive, so particularly advantageous for thin films. The theoretical background shows the possibility to access the electric field at interfaces and consequently to have a non-destructive measurement for interface state densities or fixed charges in oxides. Two more detailed examples of application of SHG characterization will be shown: passivation of silicon using thin film deposited alumina and interface analysis of silicon-on-insulator substrates.
关键词： interface states,dielectric-semiconductor interfaces,fixed oxide charges,interface electric field,second harmonic generation
更新于2025-09-04 15:30:14