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10 pages, 4510 KiB

Open AccessArticle

Improved DC and RF Characteristics of GaN-Based Double-Channel HEMTs by Ultra-Thin AlN Back Barrier Layer

by Qian Yu, Chunzhou Shi, Ling Yang, Hao Lu, Meng Zhang, Xu Zou, Mei Wu, Bin Hou, Wenze Gao, Sheng Wu, Xiaohua Ma and Yue Hao

Micromachines 2024, 15(10), 1220; https://doi.org/10.3390/mi15101220 - 30 Sep 2024

Cited by 2 | Viewed by 1511

Abstract

In order to improve the off-state and breakdown characteristics of double-channel GaN HEMTs, an ultra-thin barrier layer was chosen as the second barrier layer. The strongly polarized and ultra-thin AlN sub-barrier and the InAlN sub-barrier are great candidates. In this article, the two epitaxial structures, AlGaN/GaN/AlN/GaN (sub-AlN) HEMTs and AlGaN/GaN/InAlN/GaN (sub-InAlN) HEMTs, were compared to select a more suitable sub-barrier layer. Through TEM images of the InAlN barrier layer, the segregation of In components can be seen, which decreases the mobility of the second channel. Thus, the sub-AlN HEMTs have a higher output current density and transconductance than those of the sub-InAlN HEMTs. Because the high-quality AlN barrier layer shields the gate leakage current, a 294 V breakdown voltage was achieved by the sub-AlN HEMTs, which is higher than the 121 V of the sub-InAlN HEMTs. The current gain cut-off frequency (f_T) and maximum oscillation frequency (f_max) of the sub-AlN HEMTs are higher than that of the sub-InAlN HEMTs from low to high bias voltage. The power-added efficiency (PAE) and output power density (P_out) of the sub-AlN HEMTs are 57% and 11.3 W/mm at 3.6 GHz and 50 V of drain voltage (V_d), respectively. For the sub-InAlN HEMTs, the PAE and P_out are 41.4% and 8.69 W/mm, because of the worse drain lag ratio. Thus, the P_out of the sub-AlN HEMTs is higher than that of the sub-InAlN HEMTs. Full article

(This article belongs to the Special Issue RF and Power Electronic Devices and Applications)

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11 pages, 4214 KiB

Open AccessArticle

Influence of Gate Geometry on the Characteristics of AlGaN/GaN Nanochannel HEMTs for High-Linearity Applications

by Meng Zhang, Yilin Chen, Siyin Guo, Hao Lu, Qing Zhu, Minhan Mi, Mei Wu, Bin Hou, Ling Yang, Xiaohua Ma and Yue Hao

Micromachines 2023, 14(8), 1513; https://doi.org/10.3390/mi14081513 - 28 Jul 2023

Cited by 5 | Viewed by 2410

Abstract

In this study, AlGaN/GaN nanochannel high-electron-mobility transistors (HEMTs) with tri-gate (TGN-devices) and dual-gate (DGN-devices) structures were fabricated and investigated. It was found that the peak value of the transconductance (G_m), current gain cut-off frequency (f_T) and power gain cut-off frequency (f_max) of the TGN-devices were larger than that of the DGN-devices because of the enhanced gate control from the top gate. Although the TGN-devices and DGN-devices demonstrated flattened transconductance, f_T and f_max profiles, the first and second transconductance derivatives of the DGN-devices were lower than those of the TGN-devices, implying an improvement in linearity. With the nanochannel width decreased, the peak value of the transconductance and the first and second transconductance derivatives increased, implying the predominant influence of sidewall gate capacitance on the transconductance and linearity. The comparison of gate capacitance for the TGN-devices and DGN-devices revealed that the gate capacitance of the tri-gate structure was not simply a linear superposition of the top planar gate capacitance and sidewall gate capacitance of the dual-gate structure, which could be attributed to the difference in the depletion region shape for tri-gate and dual-gate structures. Full article

(This article belongs to the Special Issue Latest Advancements in Next-Generation Semiconductors: Materials and Devices for Wide Bandgap and 2D Semiconductors)

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14 pages, 2569 KiB

Open AccessArticle

Graphical Approach to Optimization of Maximally Efficient-Gain-Boosted Feedback Amplifiers

by Yang Xing and Ruibing Dong

Electronics 2023, 12(13), 2895; https://doi.org/10.3390/electronics12132895 - 30 Jun 2023

Cited by 3 | Viewed by 1519

Abstract

It is challenging to design high-gain amplifiers near the maximum oscillation frequency (f_max) of the transistors. This paper presents a comprehensive graphical approach to maximize the gain of feedback amplifiers with maximally efficient gain (G_ME) conception at near-fmax frequency. The complex gain-plane and the reflection-coefficient-plane are utilized to provide clear insights into both the gain and stability states of the two-port device while boosting G_ME. An efficient flowchart to synthesize feedback amplifiers is given, which optimizes the G_ME of a two-port device while ensuring the stability. A 210 GHz power amplifier in 40 nm CMOS was designed and optimized based on the proposed approach. The feedback circuit of the transistor pushes it to become potentially unstable and boosts GME. The measured peak small-signal gain was 10.48 dB at 195.33 GHz. The measured saturation output power and large-signal gain at 210 GHz were 3.04 dBm and 7.08 dB, respectively. The presented method could facilitate terahertz amplifier design. Full article

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16 pages, 5366 KiB

Open AccessReview

Heterogeneous and Monolithic 3D Integration Technology for Mixed-Signal ICs

by Jaeyong Jeong, Dae-Myeong Geum and SangHyeon Kim

Electronics 2022, 11(19), 3013; https://doi.org/10.3390/electronics11193013 - 22 Sep 2022

Cited by 22 | Viewed by 10842

Abstract

For next-generation system-on-chips (SoCs) in diverse applications (RF, sensor, display, etc.) which require high-performance, small form factors, and low power consumption, heterogeneous and monolithic 3D (M3D) integration employing advanced Si CMOS technology has been intriguing. To realize the M3D-based systems, it is important to take into account the relationship between the top and bottom devices in terms of thermal budget, electrical coupling, and operability when using different materials and various processes during integration and sequential fabrication. In this paper, from this perspective, we present our recent progress of III-V devices on Si bottom devices/circuits for providing informative guidelines in RF and imaging devices. Successful fabrication of the high-performance InGaAs high electron mobility transistors (HEMTs) on the bottom ICs, with a high unity current gain cutoff frequency (f_T) and unity power gain cutoff frequency (f_MAX) was accomplished without substrate noise. Furthermore, the insertion of an intermediate metal plate between the top and bottom devices reduced the thermal interaction. Furthermore, the InGaAs photodetectors (PDs) were monolithically integrated on Si bottom devices without thermal damage due to low process temperature. Based on the integrated devices, we successfully evaluated the device scalability using sequential fabrication and basic readout functions of integrated circuits. Full article

(This article belongs to the Special Issue Advanced CMOS Devices and Applications)

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14 pages, 6515 KiB

Open AccessArticle

Comprehensive Power Gain Assessment of GaN-SOI-FinFET for Improved RF/Wireless Performance Using TCAD

by Ajay Kumar, Neha Gupta, Amit Kumar Goyal and Yehia Massoud

Micromachines 2022, 13(9), 1418; https://doi.org/10.3390/mi13091418 - 28 Aug 2022

Cited by 11 | Viewed by 2479

Abstract

In this work, we present a radio frequency (RF) assessment of the nanoscale gallium nitride-silicon-on-insulator fin field-effect transistor (GaN-SOI-FinFET). All the performances of the device were compared with GaN-FinFET and conventional FinFET (Conv. FinFET) simultaneously. All the results show that the power gains significantly improved in terms of Gma, Gms, Stern stability factor (SS), GMT, and intrinsic delay in comparison with conventional FinFET. Current gain and unilateral power gain were also evaluated for the extraction of fT (cut-off frequency) and f_MAX, respectively. f_T and f_MAX were enhanced by 88.8% and 94.6%, respectively. This analysis was performed at several THz frequencies. Further, the parametric assessment was also performed in terms of gate length and oxide thickness to find the optimized value of gate length and oxide thickness. The implementation of GaN in the channel reduces the parasitic capacitance and paves the way for high-performance RF applications. Full article

(This article belongs to the Special Issue Advancements in MOSFET and Field Effect Devices)

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10 pages, 2468 KiB

Open AccessArticle

High-Performance CVD Bilayer MoS₂ Radio Frequency Transistors and Gigahertz Mixers for Flexible Nanoelectronics

by Qingguo Gao, Chongfu Zhang, Kaiqiang Yang, Xinjian Pan, Zhi Zhang, Jianjun Yang, Zichuan Yi, Feng Chi and Liming Liu

Micromachines 2021, 12(4), 451; https://doi.org/10.3390/mi12040451 - 16 Apr 2021

Cited by 11 | Viewed by 4125

Abstract

Two-dimensional (2D) MoS₂ have attracted tremendous attention due to their potential applications in future flexible high-frequency electronics. Bilayer MoS₂ exhibits the advantages of carrier mobility when compared with monolayer mobility, thus making the former more suitable for use in future flexible high-frequency electronics. However, there are fewer systematical studies of chemical vapor deposition (CVD) bilayer MoS₂ radiofrequency (RF) transistors on flexible polyimide substrates. In this work, CVD bilayer MoS₂ RF transistors on flexible substrates with different gate lengths and gigahertz flexible frequency mixers were constructed and systematically studied. The extrinsic cutoff frequency (f_T) and maximum oscillation frequency (f_max) increased with reducing gate lengths. From transistors with a gate length of 0.3 μm, we demonstrated an extrinsic f_T of 4 GHz and f_max of 10 GHz. Furthermore, statistical analysis of 14 flexible MoS₂ RF transistors is presented in this work. The study of a flexible mixer demonstrates the dependence of conversion gain versus gate voltage, LO power and input signal frequency. These results present the potential of CVD bilayer MoS₂ for future flexible high-frequency electronics. Full article

(This article belongs to the Special Issue Electronic Devices and Circuits Based on 2D Materials)

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5 pages, 867 KiB

Open AccessArticle

InAlGaN/GaN HEMTs at Cryogenic Temperatures

by Ezgi Dogmus, Riad Kabouche, Sylvie Lepilliet, Astrid Linge, Malek Zegaoui, Hichem Ben-Ammar, Marie-Pierre Chauvat, Pierre Ruterana, Piero Gamarra, Cédric Lacam, Maurice Tordjman and Farid Medjdoub

Electronics 2016, 5(2), 31; https://doi.org/10.3390/electronics5020031 - 22 Jun 2016

Cited by 30 | Viewed by 8667

Abstract

We report on the electron transport properties of two-dimensional electron gas confined in a quaternary barrier InAlGaN/AlN/GaN heterostructure down to cryogenic temperatures for the first time. A state-of-the-art electron mobility of 7340 cm²·V⁻¹·s⁻¹ combined with a sheet carrier density of 1.93 × 10¹³ cm⁻² leading to a remarkably low sheet resistance of 44 Ω/□ are measured at 4 K. A strong improvement of Direct current (DC) and Radio frequency (RF) characteristics is observed at low temperatures. The excellent current and power gain cutoff frequencies (f_T/f_max) of 65/180 GHz and 95/265 GHz at room temperature and 77 K, respectively, using a 0.12 μm technology confirmed the outstanding 2DEG properties. Full article

(This article belongs to the Special Issue Gallium Nitride Electronics)

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