Direct tunneling through high-<i>κ</i> amorphous HfO2: Effects of chemical modification

Wang, Yin; Yu, Zhen; Zahid, Ferdows; Liu, Lei; Zhu, Yu; Wang, Jian; Guo, Hong

doi:10.1063/1.4890010

Cited by 16 publications

(15 citation statements)

References 41 publications

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“…Figure 5 intuitively show the band alignment of ZnO/Zn 0.85 M 0.15 O (M = Mg, Cd) by plotting the local projected DOS4243 along the heterojunction direction. It can be clearly observed that the pure ZnO crystal formed type-I band alignment heterojunction with its Mg and Cd doped ternary alloys, and the band gap of pure ZnO is smaller than that of ZnMgO but larger than that of ZnCdO.…”

Section: Resultsmentioning

confidence: 99%

Composition dependent band offsets of ZnO and its ternary alloys

Yin

Chen

Wang

et al. 2017

Sci Rep

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We report the calculated fundamental band gaps of wurtzite ternary alloys Zn1−xMxO (M = Mg, Cd) and the band offsets of the ZnO/Zn1−xMxO heterojunctions, these II-VI materials are important for electronics and optoelectronics. Our calculation is based on density functional theory within the linear muffin-tin orbital (LMTO) approach where the modified Becke-Johnson (MBJ) semi-local exchange is used to accurately produce the band gaps, and the coherent potential approximation (CPA) is applied to deal with configurational average for the ternary alloys. The combined LMTO-MBJ-CPA approach allows one to simultaneously determine both the conduction band and valence band offsets of the heterojunctions. The calculated band gap data of the ZnO alloys scale as Eg = 3.35 + 2.33x and Eg = 3.36 − 2.33x + 1.77x2 for Zn1−xMgxO and Zn1−xCdxO, respectively, where x being the impurity concentration. These scaling as well as the composition dependent band offsets are quantitatively compared to the available experimental data. The capability of predicting the band parameters and band alignments of ZnO and its ternary alloys with the LMTO-CPA-MBJ approach indicate the promising application of this method in the design of emerging electronics and optoelectronics.

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Section: Resultsmentioning

confidence: 99%

Composition dependent band offsets of ZnO and its ternary alloys

Yin

Chen

Wang

et al. 2017

Sci Rep

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“…In view of the limitation of structure size in the first principles calculation, we performed an empirical WKB fitting with parameters obtained from the DFT calculations to predict the pressure-dependent conductance of pure BP devices at larger scales. Using the WKB method, the conductance G WKB can be estimated empirically by [46–50]…”

Section: Resultsmentioning

confidence: 99%

First principles modeling of pure black phosphorus devices under pressure

Rong¹,

et al. 2019

Beilstein J. Nanotechnol.

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Black phosphorus (BP) has a pressure-dependent bandgap width and shows the potential for applications as a low-dimensional pressure sensor. We built two kinds of pure BP devices with zigzag or armchair conformation, and explored their pressure-dependent conductance in detail by using first principles calculations. The zigzag BP devices and the armchair BP devices exhibit different conductance–pressure relationships. For the zigzag BP devices conductance is robust against stress when the out-of-plane pressure ratio is less than 15%, and then increases rapidly until the conductive channels are fully opened. For the armchair pure BP devices conductance decreases at first by six orders of magnitude under increasing pressure and then increases quickly with further increase of pressure until the devices enter the on-state. This shows that the pure zigzag BP devices are more suitable for the application as flexible electronic devices with almost constant conductance under small pressure, while armchair BP devices can serve as bidirectional pressure sensors. Real-space distributions of band alignments were explored to understand the different pressure-related properties. We fitted a set of parameters based on the results from the empirical Wentzel–Kramers–Brillouin method, which provides an effortless approximation to quantitatively predict the pressure-related behaviors of large pure BP devices.

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“…Besides using the above calculation method to accurately determine the band offset values, a more intuitive way to obtain the band alignment is to calculate the local projected density of states (LPDOS) of the heterojunction [56][57][58], through which we can obtain the band alignment of the heterojunction directly, and an intrinsic staggered band offset (type II band alignment) can be observed as shown in Figure 4. Clearly, the LPDOS indicated band offsets qualitatively agree well with our accurately determined band offset values.…”

Section: Resultsmentioning

confidence: 99%

Predicting band offset of lattice matched ZnO and BeCdO heterojunction from first principles

Liu

Chen

Yin

et al. 2019

Materials Research Letters

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Using first-principles approach, we calculated the band gaps of wurtzite Be 1−x Cd x O ternary alloy and the band offset of the lattice matched ZnO/Be 0.44 Cd 0.56 O[1 1 2 0] heterojunction, where the modified Becke-Johnson semi-local exchange was used to determine the band gap and the coherent potential approximation was applied to deal with doping effect in disordered alloys. The ZnO/Be 0.44 Cd 0.56 O heterojunction was determined to have a type II band alignment, with valence and conduction band offset being 0.28 and 0.50 eV, respectively. The calculation approach and procedure demonstrated here can be used to predict the band offset of more lattice matched semiconductor heterojunctions. IMPACT STATEMENT The band offsets of lattice matched ZnO/Be 0.44 Cd 0.56 O heterojunction were predicted from first principles, where band gaps of semiconductors and configuration average of disorders were both accurately and efficiently calculated.

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Direct tunneling through high-κ amorphous HfO2: Effects of chemical modification

Cited by 16 publications

References 41 publications

Composition dependent band offsets of ZnO and its ternary alloys

Composition dependent band offsets of ZnO and its ternary alloys

First principles modeling of pure black phosphorus devices under pressure

Predicting band offset of lattice matched ZnO and BeCdO heterojunction from first principles

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