Capacitance Voltage Characteristics and Electron Holography on Cubic AlGaN/GaN Heterojunctions

As, D. J.; Zado, A.; Wei, Qiyang Y.; Li, Ti; Huang, Jingyi; Ponce, Fernando

doi:10.7567/jjap.52.08jn04

Cited by 10 publications

(3 citation statements)

References 29 publications

(31 reference statements)

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“…where W, k s , 0 , A, q and V are the distance from the surface, the relative dielectric constant, the permittivity of free space, the area of the Schottky contact, the elementary charge and the applied voltage, respectively. A similar method of extraction for N C-V is also used for AlGaN/GaN heterostructures [28] and the inverse MgZnO/ZnO heterostructure [29]. The carrier concentration was calculated, assuming the relative dielectric constants of MgZnO and ZnO to be the same at 8.75 [9].…”

Section: Resultsmentioning

confidence: 99%

Two-dimensional electron gases in MgZnO/ZnO and ZnO/MgZnO/ZnO heterostructures grown by dual ion beam sputtering

Singh

Khan

Sharma

et al. 2018

J. Phys. D: Appl. Phys.

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This work reports on the formation of high-density (~1013–1014 cm−2) two-dimensional electron gas (2DEG) in ZnO-based heterostructures, grown by a dual ion beam sputtering system. We probe 2DEG in bilayer MgZnO/ZnO and capped ZnO/MgZnO/ZnO heterostructures utilizing MgZnO barrier layers with varying thickness and Mg content. The effect of the ZnO cap layer thickness on the ZnO/MgZnO/ZnO heterostructure is also studied. Hall measurements demonstrate that the addition of a 5 nm ZnO cap layer results in an enhancement of the 2DEG density by about 1.5 times compared to 1.11 1014 cm−2 for the uncapped bilayer heterostructure with the same 30 nm barrier thickness and 30 at.% Mg composition in the barrier layer. From the low-temperature Hall measurement, the sheet carrier concentration and mobility are both found to be independent of the temperature. The capacitance–voltage measurement suggests a carrier density of ~1020 cm−3, confined in 2DEG at the MgZnO/ZnO heterointerface. The results presented are significant for the optimization of 2DEG for the eventual realization of cost-effective and large-area MgZnO/ZnO-based high-electron-mobility transistors.

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Section: Resultsmentioning

confidence: 99%

Two-dimensional electron gases in MgZnO/ZnO and ZnO/MgZnO/ZnO heterostructures grown by dual ion beam sputtering

Singh

Khan

Sharma

et al. 2018

J. Phys. D: Appl. Phys.

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“…By off‐axis electron holography, electron concentration of 5.1 × 10 11 cm −2 was obtained at the AlGaN/GaN interface with a conduction‐to‐valence band offset ratio of ≈4:1, which promoted the observed electron accumulation. Without contributions from piezoelectric fields along polar axis, the existence of 2DEG at the interface could be attributed to residual background doping in the Al x Ga 1− x N and GaN …”

Section: The Off‐axis Electron Holography Schemementioning

confidence: 99%

Electron Holographic Study of Semiconductor Light‐Emitting Diodes

Gao

2017

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Semiconductor light-emitting diodes (LEDs), especially GaN-based heterostructures, are widely used in light illumination. The lack of inversion symmetry of wurtzite crystal structures and the lattice mismatch at heterointerfaces cause large polarization fields with contributions from both spontaneous polarization and piezoelectric polarization, which in turn results in obvious quantum confined stark effect. It is possible to alleviate this effect if the local electrostatic fields and band alignment induced charge redistribution can be quantitatively determined across the heterostructures. In this Concept, the applications of electron holography to investigate semiconductor LEDs are summarized. Following the off-axis electron holography scheme, the GaN-based LED heterostructures including InGaN/GaN-based quantum wells, other GaN-based quantum wells, and other forms of GaN-based LED materials are discussed, focusing on the local potential drops, polarization fields, and charge distributions. Moreover, GaAs-based LED heterostructures are briefly discussed. The in-line electron holography scheme emphasizes the capability of large area strain mapping across LED heterostructures with high spatial resolution and accuracy, which is combined with quantitative electrostatic measurements and other advanced transmission electron microscopy characterizations to provide an overall nanometer scale perspective of LED devices for further improvement in their electric and optical properties.

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“…Accordingly, various TEM-based methods have already been applied to detect electric fields. By now especially electron holography, in which the electrostatic potential is measured, [9][10][11][12][13] and differential phase contrast imaging (DPC), [14][15][16] where the shift of the diffraction pattern due to the Coulomb interaction of the impinging electrons with the sample is detected, [17] were used. More recently, four-dimensional scanning transmission electron microscopy (4D-STEM) was utilized to detect the shifts of the electron probe in terms of momentum-resolved STEM (MRSTEM).…”

Section: Introductionmentioning

confidence: 99%

Measuring Spatially‐Resolved Potential Drops at Semiconductor Hetero‐Interfaces Using 4D‐STEM

et al. 2023

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Characterizing long‐range electric fields and built‐in potentials in functional materials at nano to micrometer scales is of supreme importance for optimizing devices, e.g., the functionality of semiconductor hetero‐structures or battery materials is determined by the electric fields established at interfaces which can also vary spatially. In this study, momentum‐resolved four‐dimensional scanning transmission electron microscopy (4D‐STEM) is proposed for the quantification of these potentials and the optimization steps required to reach quantitative agreement with simulations for the GaAs/AlAs hetero‐junction model system are shown. Using STEM the differences in the mean inner potentials (∆MIP) of two materials forming an interface and resulting dynamic diffraction effects have to be considered. This study shows that the measurement quality is significantly improved by precession, energy filtering and a off‐zone‐axis alignment of the specimen. Complementary simulations yielding a ∆MIP of 1.3 V confirm that the potential drop due to charge transfer at the intrinsic interface is ≈0.1 V, in agreement with experimental and theoretical values found in literture. These results show the feasibility of accurately measuring built‐in potentials across hetero‐interfaces of real device structures and its promising application for more complex interfaces of other polycrystalline materials on the nanometer scale.

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Capacitance Voltage Characteristics and Electron Holography on Cubic AlGaN/GaN Heterojunctions

Cited by 10 publications

References 29 publications

Two-dimensional electron gases in MgZnO/ZnO and ZnO/MgZnO/ZnO heterostructures grown by dual ion beam sputtering

Two-dimensional electron gases in MgZnO/ZnO and ZnO/MgZnO/ZnO heterostructures grown by dual ion beam sputtering

Electron Holographic Study of Semiconductor Light‐Emitting Diodes

Measuring Spatially‐Resolved Potential Drops at Semiconductor Hetero‐Interfaces Using 4D‐STEM

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