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.
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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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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.
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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
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.
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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.
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References
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TL;DR: In this paper, the impact of phase segregation, structural imperfections, and alloy inhomogeneities on the phonon dynamics and electronic states of MgxZn1−xO thin films were studied via selective resonant Raman scattering (SRRS) and Urbach analyses, respectively.
Abstract: The MgxZn1−xO alloy system is emerging as an environmentally friendly choice in ultraviolet lighting and sensor technologies. Knowledge of defects which impact their optical and material properties is a key issue for utilization of these alloys in various technologies. The impact of phase segregation, structural imperfections, and alloy inhomogeneities on the phonon dynamics and electronic states of MgxZn1−xO thin films were studied via selective resonant Raman scattering (SRRS) and Urbach analyses, respectively. A series of samples with Mg composition from 0–68% were grown using a sputtering technique, and the optical gaps were found to span a wide UV range of 3.2–5.8 eV. The extent of the inherent phase segregation was determined via SRRS using two UV-laser lines to achieve resonance with the differing optical gaps of the embedded cubic and wurtzite structural domains. The occurrence of Raman scattering from cubic structures is discussed in terms of relaxation of the selection rules due to symmetry brea...
33 citations
"Drain Current Optimization in DIBS-..." refers background in this paper
...6 in the barrier layer of the MgxZn1−x O, which is difficult to fabricate without causing phase separation [3]–[5]....
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33 citations
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...Prior to film deposition, in order to remove organic contaminants and native oxide, the Si substrate is thoroughly cleaned, details of which are described in our previous work [14]....
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TL;DR: In this article, the effects of postannealing on Ti/Au-MgZnO contact and n-mgZNO/p-Si heterojunction ultraviolet-B photodetector's performance are investigated.
Abstract: Effects of postannealing on Ti/Au-MgZnO contact and n-MgZnO/p-Si heterojunction ultraviolet-B photodetector's performance are investigated. It is found that the out diffusion of oxygen from MgZnO and its bonding with Ti at the interface have significant influences on the properties of Ti/MgZnO interface and photodetector. The persistent photocurrent observed in the annealed device is attributed to the oxygen vacancies near the interface, consistent with the theoretical calculations. It is revealed that the reaction at metal/MgZnO interface possibly plays a key role and even dominates the MgZnO p-n heterojunction ultraviolet detectors' performances.
28 citations
"Drain Current Optimization in DIBS-..." refers background in this paper
...This could probably be due to the formation of a TiOx monolayer at the MgZnO–Ti interface [24]....
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TL;DR: In this paper, a novel metal scheme for ohmic contact on AlGaN/GaN high-electron-mobility transistors was reported, which showed minimum metal out-diffusion and sharp edge acuity at high-temperature annealing, which facilitates aggressive scaling of source-drain separation.
Abstract: In this letter, we have reported a novel metal scheme Ti/Au/Al/Ni/Au for ohmic contact on AlGaN/GaN high-electron-mobility transistors. The reported metal scheme is observed to show minimum metal out-diffusion and sharp edge acuity at high-temperature annealing, which facilitates aggressive scaling of source–drain separation ( ${L} _{\textsf {SD}}$ ). We have demonstrated ${L} _{\textsf {SD}}$ as low as 300 nm with gate length ( ${L} _{\textsf {g}}$ ) of 100 nm for this metal stack. We observed improvement in ON-resistance ( ${R} _{\mathrm{\scriptscriptstyle ON}}$ ) from 3 to $1.25~\Omega \cdot$ mm, transconductance ( ${g} _{\textsf {m}}$ ) from 276 to 365 mS/mm, saturation drain current ( ${I} _{\textsf {DS,sat}}$ ) from 906 to 1230 mA/mm, and unity current gain frequency ( ${f} _{\textsf {T}}$ ) from 70 to 93 GHz by scaling ${L} _{\textsf {SD}}$ from $3~\mu \text{m}$ to 300 nm. The gate lengths for all devices were 100 nm.
27 citations
27 citations
"Drain Current Optimization in DIBS-..." refers background in this paper
...[7] have achieved ns ∼ 1014 cm−2 for x ≥ 0....
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...The SAED patterns of the MZO and MCO-II show a nearly crystalline lattice pattern of the grown heterostructures, which can be attributed to the pattern observed in the [1̄ 2 1̄ 0] axis of the wurtzite crystal [7], as opposed to the definitive...
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...The drawback observed in the DIBS-grown MCO heterostructure was one order lower electron mobility (μ ≈ 3 cm2V−1s−1) [9], when compared to the sputtered MZO heterostructure (∼30 cm2V−1s−1) [6], [7] at barrier layer thickness (tb) = 30 nm and x = 0....
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