Temperature and time dependent electron trapping in Al2O3 thin films onto AlGaN/GaN heterostructures

Fiorenza, Patrick; Schilirò, Emanuela; Greco, Giuseppe; Vivona, Marilena; Cannas, Marco; Giannazzo, Filippo; Nigro, Raffaella Lo; Roccaforte, Fabrizio

doi:10.1016/j.apsusc.2021.152136

Cited by 3 publications

(2 citation statements)

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“…Nevertheless, the electron trapping inside the Al 2 O 3 gate insulator in GaN MISHEMTs can be used to intentionally induce a positive shift in the threshold voltage and finally obtain a normally-off operation [121]. In this context, Fiorenza et al [133] recently studied the temperature stability of these effects, demonstrating the presence of two competitive electron trapping/de-trapping mechanisms in Al 2 O 3 films, which were likely related to the presence of oxygen vacancies in the material.…”

Section: Binary High-κ Oxides For Gan-based Mishemtsmentioning

confidence: 99%

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

et al. 2022

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High-κ dielectrics are insulating materials with higher permittivity than silicon dioxide. These materials have already found application in microelectronics, mainly as gate insulators or passivating layers for silicon (Si) technology. However, since the last decade, the post-Si era began with the pervasive introduction of wide band gap (WBG) semiconductors, such as silicon carbide (SiC) and gallium nitride (GaN), which opened new perspectives for high-κ materials in these emerging technologies. In this context, aluminium and hafnium oxides (i.e., Al2O3, HfO2) and some rare earth oxides (e.g., CeO2, Gd2O3, Sc2O3) are promising high-κ binary oxides that can find application as gate dielectric layers in the next generation of high-power and high-frequency transistors based on SiC and GaN. This review paper gives a general overview of high-permittivity binary oxides thin films for post-Si electronic devices. In particular, focus is placed on high-κ binary oxides grown by atomic layer deposition on WBG semiconductors (silicon carbide and gallium nitride), as either amorphous or crystalline films. The impacts of deposition modes and pre- or postdeposition treatments are both discussed. Moreover, the dielectric behaviour of these films is also presented, and some examples of high-κ binary oxides applied to SiC and GaN transistors are reported. The potential advantages and the current limitations of these technologies are highlighted.

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Section: Binary High-κ Oxides For Gan-based Mishemtsmentioning

confidence: 99%

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

et al. 2022

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“…In this work we use a precise method to calculate the total number of induced trapped charges, -∆N it , which is added to the Al 2 O 3 /GaN interface after stress is applied in each sweep. This method is of improved accuracy compared to the method of multiplying ∆V FB by C OX over q that was presented earlier [29][30][31]. The first step is the calculation of the accumulated charge of a pristine fresh forward sweep (ffs) by integrating the capacitance between the flat band voltage, V FB 0 , to the maximum stress bias of each sweep V max(i) :…”

Section: Interface Charge Densitiesmentioning

confidence: 99%

Effects of post metallization annealing on Al₂O₃ atomic layer deposition on n-GaN

Tadmor

Brusaterra

Bahat‐Treidel

et al. 2022

Semicond. Sci. Technol.

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The chemical, physical and electrical properties and the robustness of post metallization annealed Al2O3 atomic layers deposited on n-type GaN are investigated in this work. Planar metal insulator capacitors are used to demonstrate a gate-first with following ohmic contacts formation at elevated temperature up to 600°C process flow. X-ray photoelectron spectroscopy indicates that no new bonds in the Al2O3 layer are formed due to exposure to the elevated annealing temperature. X-ray diffraction measurements show no crystallization of the oxide layer. Atomic force microscopy shows signs of degradation of the sample annealed at 600°C. Electrical measurements indicate that the elevated annealing temperature results in an increase of the oxide depletion and the deep depletion capacitances simultaneously, that results in a reduction of the flat band voltage to zero, which is explained by fixed oxide charges curing. A forward bias step stress capacitance measurement shows that the total number of induced trapped charges are not strongly affected by the elevated annealing temperatures. Interface trap density of states analysis shows the lowest trapping concentration for the capacitor annealed at 500°C. Above this temperature, the interface trap density of states increases. When all results are takes into consideration, we have found that the process thermal budget allows for an overlap between the gate oxide post metallization annealing and the ohmic contact formation at 500°C.

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Aluminum Frenkel defects cause hysteresis in Al2O3/AlGaN capacitors

Deretzis

Fiorenza

Tommaso

et al. 2022

Journal of Applied Physics

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[Formula: see text]/AlGaN metal-oxide-semiconductor capacitors show a hysteretic behavior in their capacitance vs voltage characteristics, often attributed to near-interface traps deriving from defects within the oxide layer. The origin as well as the structural/electronic properties of such defects are still strongly debated in the literature. Here, we use ab initio molecular dynamics and the climbing-image nudged elastic band method to show that aluminum Frenkel defects give rise to bistable trap states in disordered and stoichiometric [Formula: see text]. Based on these results, we propose a calibrated polaron model representing a distribution of individually interacting energy levels with an internal reconfiguration mode and coupled to continuous bands of carriers to explain the hysteresis mechanism in [Formula: see text]/AlGaN capacitors.

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Temperature and time dependent electron trapping in Al2O3 thin films onto AlGaN/GaN heterostructures

Cited by 3 publications

References 42 publications

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

Effects of post metallization annealing on Al₂O₃ atomic layer deposition on n-GaN

Aluminum Frenkel defects cause hysteresis in Al2O3/AlGaN capacitors

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Temperature and time dependent electron trapping in Al2O3 thin films onto AlGaN/GaN heterostructures

Cited by 3 publications

References 42 publications

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

Structural and Insulating Behaviour of High-Permittivity Binary Oxide Thin Films for Silicon Carbide and Gallium Nitride Electronic Devices

Effects of post metallization annealing on Al2O3 atomic layer deposition on n-GaN

Aluminum Frenkel defects cause hysteresis in Al2O3/AlGaN capacitors

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Effects of post metallization annealing on Al₂O₃ atomic layer deposition on n-GaN