Record 94 GHz performance from N-polar GaN-on-Sapphire MIS-HEMTs: 5.8 W/mm and 38.5% PAE

Li, W.; Romanczyk, Brian; Akso, Emre; Guidry, Matthew; Hatui, Nirupam; Wurm, Christian; Liu, W.; Shrestha, Pawana; Collins, Henry; Clymore, Christopher; Keller, S.; Mishra, Umesh K.

doi:10.1109/iedm45625.2022.10019475

Cited by 9 publications

(6 citation statements)

References 8 publications

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“…As a result, millimeter-wave N-polar HEMTs have demonstrated record values of power density and efficiency (8 W/mm at 10, 34, and 94 GHz, with PAE of 28.8% at 94 GHz) [24]. Recently, N-polar GaN-on-sapphire deep recess MIS-HEMTs have reached a high 8.8-dB linear gain in the W -band at 94 GHz at a 260-mA/mm current density bias point, enabling excellent output power density of 5.83 W/mm with record 38.5% PAE at 14 V [25]. At 12-V, those devices demonstrated an even higher PAE of 40.2%, with an associated 4.85 W/mm of output power density.…”

Section: State-of-the-art Of Microwave Andmentioning

confidence: 99%

“…In fact, N-polar GaN offers a much wider design space with respect to the Ga-polar counterpart. In N-polar devices [23], [24], [25], [65], [66], [67], [68], [69], [70], [71], [72], the AlGaN barrier layer is placed below the GaN channel layer and the 2DEG is formed between the gate contact and the (Al)GaN heterointerface. As a consequence, the distance between the 2DEG and the gate can be reduced without affecting AlGaN thickness and channel conductivity, thus achieving a better channel control and a higher transconductance.…”

Section: Short-channel Effects In Gan Hemtsmentioning

confidence: 99%

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Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Zanoni,

De Santi,

Gao

et al. 2024

IEEE Trans. Electron Devices

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Application of gallium nitride high-electronmobility transistors (GaN HEMTs) to millimeter-wave power amplifiers requires gate length scaling below 150 nm: in order to control short-channel effects, the gate-to-channel distance must be decreased, and the device epitaxial structure has to be completely redesigned. A high 2-D electron gas (2DEG) carrier density can be preserved even with a very thin top barrier layer by substituting AlGaN with AlN, InAl(Ga)N, or ScAlN. Moreover, to prevent interaction of hot electrons with compensating impurities and defects in the doped GaN buffer, the latter has to be separated from the channel by a back barrier. Other device designs consist in adopting a graded channel (which controls the electric field) or to adopt nitrogen-polar (N-polar) GaN growth (which decreases the distance between gate and channel, thus attenuating short-channel effects). The aim of this article is to review the various options for controlling short-channel effects, improve off-state characteristics, and reduce drain-source leakage current. Advantages and potential drawbacks of each proposed solution are analyzed in terms of current collapse (CC), dispersion effects, and reliability.

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Section: State-of-the-art Of Microwave Andmentioning

confidence: 99%

Section: Short-channel Effects In Gan Hemtsmentioning

confidence: 99%

Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Zanoni,

De Santi,

Gao

et al. 2024

IEEE Trans. Electron Devices

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“…Currently, GaN HEMTs are mostly based on Ga-polar epilayers along the c-axis. As a counterpart, the N-polar GaN-based HEMT is recently emerging and shows immense potential to further enhance device performance [4,5]. Such devices are normally based on the N-polar GaN/AlGaN heterojunction, where the GaN channel layer on the surface has a narrower bandgap and lower electron barrier, as well as AlGaN as an inherent back barrier.…”

Section: Introductionmentioning

confidence: 99%

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

Guo,

Yu,

Zhang

et al. 2024

Crystals

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This article presents the utilization of the chemical–mechanical polishing (CMP) method to fabricate high-performance N-polar GaN/AlGaN metal–insulator–semiconductor high-electron-mobility transistors (MIS-HEMTs) through layer transfer technology. The nucleation and buffer layers were removed via CMP to attain a pristine N-polar GaN surface with elevated smoothness, featuring a low root-mean-square (RMS) roughness of 0.216 nm. Oxygen, carbon, and chlorine impurity elements content were low after the CMP process, as detected via X-ray photoelectron spectroscopy (XPS). The electrical properties of N-polar HEMTs fabricated via CMP exhibited a sheet resistance (Rsh) of 244.7 Ω/sq, a mobility of 1230 cm2/V·s, and an ns of 2.24 × 1013 cm−2. Compared with a counter device fabricated via inductively coupled plasma (ICP) dry etching, the CMP devices showed an improved output current of 756.1 mA/mm, reduced on-resistance of 6.51 Ω·mm, and a significantly reduced subthreshold slope mainly attributed to the improved surface conditions. Meanwhile, owing to the MIS configuration, the reverse gate leakage current could be reduced to as low as 15 μA/mm. These results highlight the feasibility of the CMP-involved epitaxial layer transfer (ELT) technique to deliver superior N-polar GaN MIS-HEMTs for power electronic applications.

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“…GaN-based HEMTs have been widely investigated for next-generation wireless communication and power electronics applications [ 1 , 2 , 3 , 4 ]. Owing to the high breakdown voltage and high electron velocity, they exhibit excellent RF power performance at high frequencies.…”

Section: Introductionmentioning

confidence: 99%

“…Owing to the high breakdown voltage and high electron velocity, they exhibit excellent RF power performance at high frequencies. GaN HEMTs fabricated on sapphire substrate were demonstrated to be operated at 94 GHz with an output power density of 5.8 W/mm and a power-added efficiency of 38.5% [ 3 ]. Moreover, for the purposes of keeping costs low and integrating with Si-based devices, GaN-on-Si technology has also been developed [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Analysis of Trapping Effect on Large-Signal Characteristics of GaN HEMTs Using X-Parameters and UV Illumination

et al. 2023

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GaN high-electron-mobility transistors (HEMTs) have attracted widespread attention for high-power microwave applications, owing to their superior properties. However, the charge trapping effect has limitations to its performance. To study the trapping effect on the device large-signal behavior, AlGaN/GaN HEMTs and metal-insulator-semiconductor HEMTs (MIS-HEMTs) were characterized through X-parameter measurements under ultraviolet (UV) illumination. For HEMTs without passivation, the magnitude of the large-signal output wave (X21FB) and small-signal forward gain (X2111S) at fundamental frequency increased, whereas the large-signal second harmonic output wave (X22FB) decreased when the device was exposed to UV light, resulting from the photoconductive effect and suppression of buffer-related trapping. For MIS-HEMTs with SiN passivation, much higher X21FB and X2111S have been obtained compared with HEMTs. It suggests that better RF power performance can be achieved by removing the surface state. Moreover, the X-parameters of the MIS-HEMT are less dependent on UV light, since the light-induced performance enhancement is offset by excess traps in the SiN layer excited by UV light. The radio frequency (RF) power parameters and signal waveforms were further obtained based on the X-parameter model. The variation of RF current gain and distortion with light was consistent with the measurement results of X-parameters. Therefore, the trap number in the AlGaN surface, GaN buffer, and SiN layer must be minimized for a good large-signal performance of AlGaN/GaN transistors.

show abstract

Record 94 GHz performance from N-polar GaN-on-Sapphire MIS-HEMTs: 5.8 W/mm and 38.5% PAE

Cited by 9 publications

References 8 publications

Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

Microwave and Millimeter-Wave GaN HEMTs: Impact of Epitaxial Structure on Short-Channel Effects, Electron Trapping, and Reliability

High-Performance N-Polar GaN/AlGaN Metal–Insulator–Semiconductor High-Electron-Mobility Transistors with Low Surface Roughness Enabled by Chemical–Mechanical-Polishing-Incorporated Layer Transfer Technology

Analysis of Trapping Effect on Large-Signal Characteristics of GaN HEMTs Using X-Parameters and UV Illumination

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