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Journal ArticleDOI

Drain Current Optimization in DIBS-Grown MgZnO/CdZnO HFET

08 May 2020-IEEE Transactions on Electron Devices (Institute of Electrical and Electronics Engineers (IEEE))-Vol. 67, Iss: 6, pp 2276-2281
TL;DR: In this article, a dual-ion beam sputtering (DIBS)-grown MgZnO/CdZnOs (MCO)-based gateless heterostructure field effect transistor (HFET) is presented.
Abstract: This article reports the fabrication of a dual-ion beam sputtering (DIBS)-grown MgZnO/CdZnO (MCO)-based gateless heterostructure field-effect transistor (HFET). In addition, this article presents that by introducing a 30-nm yttria spacer layer, the crystallinity of the CdZnO buffer layer can be enhanced and the interface roughness at the heterojunction of the MCO heterostructure can be reduced. Furthermore, the source and drain metal contacts were optimized for the least specific contact resistivity ( $\boldsymbol {\rho }_{c}$ ) yielding metal combination and annealing conditions. The results suggest that the introduction of the yttria spacer layer improves the overall conductance [product of sheet carrier density ( ${n}_{s}$ ) and electron mobility ( $\boldsymbol {\mu }$ )] of MCO up to $3.5\times 10^{15}\,\,\text{V}^{-1}\text{s}^{-1}$ compared to $9\times 10^{14}\,\,\text{V}^{-1}\text{s}^{-1}$ in the non-yttria spacer-based MCO. In addition, the drain current ( ${I}_{d}$ )–drain voltage ( ${V}_{d}$ ) characteristic of the as-developed yttria spacer-based MCO HFET shows a high drain current value (~400 mA/mm). These results establish the DIBS-grown MCO heterostructure as a viable option for low-cost HFETs necessary for the fabrication of large-scale HFET-based power and sensor devices.
Citations
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Journal ArticleDOI
TL;DR: In this article, a dual ion beam sputtering (DIBS) system at different deposition conditions in terms of ion beam power, substrate temperature, and time cessation between deposition of successive layers is discussed systematically.
Abstract: Multiple quantum wells (MQWs) of CdZnO/ZnO are realized, for the first time, by dual ion beam sputtering (DIBS) system at different deposition conditions in terms of ion beam power, substrate temperature, and time cessation between deposition of successive layers. The effects of DIBS deposition conditions are analyzed by secondary ion mass spectroscopy (SIMS) and high-resolution transmission electron microscopy (HRTEM) and discussed systematically. The SIMS analysis has been used for depth profiling of CdZnO/ZnO-based MQWs structure. The deposition of CdZnO/ZnO-based MQW structure performed at 100 °C with time cessation of 30 min between successive layer growth and ion beam power of 14 W has displayed the best results in terms of distinct well and barrier layers formation. This work also includes an analytical study of CdZnO/ZnO-based MQW solar cell (MQWSC), in which a study is performed for solar irradiance dependence of performance parameters to explore the potential use of CdZnO/ZnO-based MQWSC for concentrator solar cell (SC). The short-circuit current density increases from 0.12 to 57.98 mA/cm2, the open-circuit voltage rises from 2.60 to 2.77 V, and the photon conversion efficiency is from 2.85% to 3.04%, as solar irradiance increases from 0.1 to 50 suns. The results show that the performance of SCs can be improved by using concentrators and also explore the possibility of efficiently absorbing short-wavelength photons.

10 citations


Cites background from "Drain Current Optimization in DIBS-..."

  • ...application displaying strong 2-D electron gas density (2DEG) [13], [14]....

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Journal ArticleDOI
TL;DR: In this paper , a stable, highly scalable, reproducible, Y2O3-based memristive crossbar array of (15 × 12) on silicon by utilizing a dual ion beam sputtering system was reported.
Abstract: Transition metal oxides play a very important role to develop the memristive crossbar array for nonvolatile memory for storage and logic operations. However, the development of a high-density memristive crossbar array for complex applications is restricted due to low device yield and high device-to-device (D2D) and cycle-to-cycle (C2C) variability in device switching voltages. Here, we report the fabrication of a stable, highly scalable, reproducible, Y2O3-based memristive crossbar array of (15 × 12) on silicon by utilizing a dual ion beam sputtering system. The fabricated crossbar array exhibits the intrinsic nonlinear characteristics of the memristive element by displaying a high endurance (∼7 × 105 cycles), high current ratio (>200), good retention (∼1.5 × 105 s), high device yield, low device-to-device (D2D) (0.25), and cycle-to-cycle (C2C) (0.608) variability in the SET/RESET voltages of the memristive device, which can be further suitable for analog computation and logic operations.

7 citations

Journal ArticleDOI
TL;DR: In this article , the electrical performance analysis of a memristive crossbar array (MCA) based on a large Si (100) wafer having a 3-inch diameter by utilizing dual-ion beam sputtering (DIBS) system is reported.
Abstract: Here, we report the electrical performance analysis of a Y2O3-based memristive crossbar array (MCA) of ( $30\,{\times }\,25$ ) on a large Si (100) wafer having a 3-inch diameter by utilizing dual-ion beam sputtering (DIBS) system. The MCA is highly stable and exhibits repeatable and reproducible resistive switching responses in terms of consistent resistive switching voltages ( ${V}_{{\mathrm {SET}}}$ and ${V}_{{\mathrm {RESET}}}$ ). The devices in the MCA efficiently depict the impact of device area scaling on the switching voltage parameters. The fabricated devices also show low device-to-device (D2D) variability in ${V}_{{\mathrm {SET}}}$ (2.64%) ${V}_{{\mathrm {RESET}}}$ (10.13%) and ultralow cycle-to-cycle (C2C) variability in ${V}_{{\mathrm {SET}}}$ (0.2%) and ${V}_{{\mathrm {RESET}}}$ (1.07%). Furthermore, this work also experimentally probes the impacts of various input signal parameters such as applied voltage, compliance current, and pulsewidth (PW) on the variability parameters.

7 citations

Journal ArticleDOI
TL;DR: In this article , the authors report an implementation of a memristive crossbar array (MCA) out of a total dimension of ( $30\times25$ ) array fabricated by utilizing a dual ion beam sputtering (DIBS) system.
Abstract: Here, we report an implementation of ( $8\times8$ ) $\text{Y}_{{2}}\text{O}_{{3}}$ -based memristive crossbar array (MCA) out of a total dimension of ( $30\times25$ ) array fabricated by utilizing a dual ion beam sputtering (DIBS) system. The selected ( $8\times8$ ) MCA is further used to electrically write random alphabets and perform synaptic learning characteristics to perform analog and neuromorphic computing applications. The MCA effectively exhibits multiple current levels and mimics various artificial synaptic properties with superior bidirectional switching responses. The MCA mimics potentiation, depression, and different Hebbian learning-based spike-time-dependent plasticity rules, suggesting the importance of the $\text{Y}_{{2}}\text{O}_{{3}}$ -based MCA for large-scale neuromorphic and analog computations. This work provides different insights into the design of an artificial synapse by utilizing $\text{Y}_{{2}}\text{O}_{{3}}$ as a switching oxide in memristors.

3 citations

Journal ArticleDOI
05 Jan 2022
TL;DR: The fabrication of an Y2O3-based memristive crossbar array along with an analytical model to evaluate the performance of the Memristive array system and the obtained results confirm that the effect of variation in electrical stimuli on forgetting and retention is similar to the biological brain.
Abstract: Here, we report the fabrication of an Y2O3-based memristive crossbar array along with an analytical model to evaluate the performance of the memristive array system to understand the forgetting and retention behavior in the neuromorphic computation. The developed analytical model is able to simulate the highly dense memristive crossbar array-based neural network of biological synapses. These biological synapses control the communication efficiency between neurons and can implement the learning capability of the neurons. During electrical stimulation of the memristive devices, the memory transition is exhibited along with the number of applied voltage pulses, which is analogous to the real human brain functionality. Further, to obtain the forgetting and retention behavior of the memristive devices, a modified window function equation is proposed by incorporating two novel internal state variables in the form of forgetting rate and retention. The obtained results confirm that the effect of variation in electrical stimuli on forgetting and retention is similar to that of the biological brain. Therefore, the developed analytical memristive model can further be utilized in the memristive system to develop real-world applications in neuromorphic domains.

2 citations

References
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Journal ArticleDOI
TL;DR: In this paper, the non-Markovian gain model was used to investigate the properties of CdZnO/MgZnOs structures with the depolarization of an internal field, and the Mg composition was selected to give zero internal field for a given Cd composition.
Abstract: Electronic and optical properties of CdZnO/MgZnO quantum well (QW) structures with the depolarization of an internal field are investigated by using the non-Markovian gain model. The Mg composition is selected to give zero internal field for a given Cd composition. The Mg content to give zero internal field is found to increase with increasing Cd content. The peak gain is improved with increasing Cd composition in a range of Cd<0.07 because a quasi-Fermi-level separation rapidly increases with the Cd composition. However, it begins to decrease when the Cd composition exceeds 0.07.

25 citations


"Drain Current Optimization in DIBS-..." refers background in this paper

  • ...In addition, the use of abundant low-cost ZnO substrates [27], [28] will further decrease the unit device price of the DIBS-...

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Journal ArticleDOI

24 citations


"Drain Current Optimization in DIBS-..." refers methods in this paper

  • ...All the layers were deposited using commercially available sputtering targets [10]....

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  • ...This article attempts to establish a DIBS-grown MCO heterostructure for viable HFET applications alongside the MBEgrown MZO, due to several advantages of the DIBS growth technique, such as superior compositional stoichiometry and thin-film uniformity with better film adhesion over a larger substrate surface area [10], along with its large-area electronics compatibility and, hence, cost-effectiveness....

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Journal ArticleDOI
TL;DR: In this paper, the authors investigated the 2D mobility of two-dimensional electron gases in MgZnO/ZnOs with interface roughness effects using path-integral framework.
Abstract: Mobility of two-dimensional electron gases in MgZnO/ZnO heterostructures with interface roughness effects was investigated theoretically using path-integral framework. We modelled the roughness-induced fluctuation by including two major effects, i.e. the electron and polarization-induced positive charge concentrations. We showed that both effects cause the scattering potential in the in-plane direction and hence affect the 2D mobility. In this work, we treated both electron and polarization-induced positive charge concentrations as equally important factors and then calculated the electron mobility and compared with the experimental result of Mg0.2Zn0.8O/ZnO heterostructure at high-electron concentrations. We found that the fitting parameters Δ = 0.26 nm, Λ = 2.5 nm gave good description to the mobility data. We also showed that neglecting the polarization-induced positive charge concentration led to overestimating the 2D mobility.

23 citations


"Drain Current Optimization in DIBS-..." refers result in this paper

  • ...and dislocation density at the heterointerface has been reported to improve the μ values in the MZO heterostructures, in the previous literature studies [16], [17]....

    [...]

Journal ArticleDOI
TL;DR: In this article, the authors studied factors that dominate the mode transformation of resistive switching in yttria-based memristive devices and reported a forming-free Al/Y2O3/Al based memristor fabricated by dual ion beam sputtering without any post-processing steps.
Abstract: In this report, we study factors that dominate the mode transformation of resistive switching (RS) in yttria based memristive devices. It is found that amorphous yttria films are more suitable for RS whereas highly crystalline films are counterproductive for RS. The transformation from unipolar to bipolar resistive switching mode is demonstrated in our devices via moving from a system of single Schottky barrier diode (SBD) to double SBD. The conduction mechanism behind these transformation mechanisms is found to be predominantly interfacial. We also report a forming-free Al/Y2O3/Al based memristor fabricated by the dual ion beam sputtering without any post-processing steps for the first time. It shows stable switching behavior for >29 000 cycles with good retention (105 s) characteristics.

23 citations


"Drain Current Optimization in DIBS-..." refers background in this paper

  • ...this article introduces a 30-nm Y2O3 (yttria), optimized for cubic crystallinity in [11], as a spacer layer between the Si substrate and the CdZnO buffer layer....

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Journal ArticleDOI
TL;DR: In this article, the role of dislocation scattering in electron mobility in ZnMgO/ZnO heterostructures was studied and it was found that dislocation was dominant in the low-electron concentration region.
Abstract: The role of dislocation scattering in electron mobility in ZnMgO/ZnO heterostructures was studied. It was found that dislocation scattering was dominant in the low-electron concentration region. The total low-temperature mobility was calculated by considering dislocation scattering and interface-roughness scattering (IRS) together. The sheet density of dislocations was chosen as Ndis=1.5 × 108 cm-2 and the IRS parameters were Δ = 5.206 and Λ = 30 Å. We obtained a good fit between our calculated results and experimental data reported in the works referenced.

12 citations


"Drain Current Optimization in DIBS-..." refers result in this paper

  • ...and dislocation density at the heterointerface has been reported to improve the μ values in the MZO heterostructures, in the previous literature studies [16], [17]....

    [...]