Room temperature microwave oscillations in GaN/AlN resonant tunneling diodes with peak current densities up to 220 kA/cm2

Encomendero, Jimy; Yan, Rusen; Verma, Amit; Islam, S. M.; Protasenko, Vladimir; Rouvimov, Sergei; Fay, Patrick; Jena, Debdeep; Xing, Huili Grace

doi:10.1063/1.5016414

Cited by 57 publications

(49 citation statements)

References 36 publications

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“…The simulation results are shown in Figure , from which it can be seen that the peak current decreases with the increase in barrier width, consistent with the previous theoretical analysis and experimental results . Fortunately, under the current epitaxial technology conditions, it is feasible to use molecular beam epitaxy to grow 2 nm (≈8 ML) high‐quality AlGaN epitaxial layers on commercially available n‐GaN substrates with dislocation densities <5 × 10 4 cm 2 . By balancing the actual growth process with the device performance, we use the realizable thickness of the 2 nm epitaxial layer as the thickness of our simulation.…”

Section: Resultssupporting

confidence: 80%

“…To improve the peak current density and peak‐to‐valley current ratio (PVCR), we propose an asymmetric GaN‐based TBRTD. First, GaN exhibits excellent material properties compared with traditional materials, such as high peak electron velocity, high saturation velocity, and so on; thus, it can achieve a high current density for RTDs. Second, a turning of the electron tunneling from the traditional 3D–2D mode to 2D–2D mode for asymmetric RTDs significantly increases the peak current and therefore raises the PVCR value.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Modeling of Triple‐Barrier Resonant‐Tunneling Diodes Based on AlGaN/GaN Heterostructures

Rong

Yang

Zhao

et al. 2019

Physica Status Solidi (a)

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Herein, the performance of asymmetric triple‐barrier resonant‐tunneling diodes (TBRTDs) based on AlGaN/GaN heterostructures is investigated using numerical simulation. TBRTD can yield the current–voltage characteristics exhibiting two negative differential resistance (NDR) regions. Investigations show that the peak‐to‐valley current ratio (PVCR) can approach the value as high as 12.3 and the peak current density remains at a high value of 2 × 105 A cm−2 for the first NDR region, whereas the PVCR has a value of 2 and the peak current density can reach as high as the value of 9 × 105 A cm−2 for the second NDR region. Analysis shows that the introduction of the second quantum well (QW2) beside the main quantum well (QW1) can suppress the leakage current and alters the electron tunneling, which significantly improve PVCR and the reproducibility of NDR characteristic. An appropriate adjustment of QW2 and the Al component in the barrier can effectively modulate the number of NDR regions and their performances, which gives us great flexibility in device design.

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Section: Resultssupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Theoretical Modeling of Triple‐Barrier Resonant‐Tunneling Diodes Based on AlGaN/GaN Heterostructures

Rong

Yang

Zhao

et al. 2019

Physica Status Solidi (a)

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“…The prominent feature of RTD is the existence of NDR region in the I‐V curve . The inset of Figure shows the I‐V curves at room temperatures for an RTD composed of a thin GaN quantum well sandwiched by two AlN tunneling barriers . There exists the NDR region when the current is larger than a critical value, where RTD oscillators are operated.…”

Section: Simulation Of Rtd Terahertz Oscillatormentioning

confidence: 99%

“…Analytical fit for the velocity‐field relation of resonant tunneling diodes (RTD) oscillators at room temperature T = 300 K. The inset is the I‐V curves for an GaN/AlN RTD at room temperature [Color figure can be viewed at wileyonlinelibrary.com]…”

Section: Simulation Of Rtd Terahertz Oscillatormentioning

confidence: 99%

Oscillations up to terahertz frequency in resonant tunneling diodes

Feng

2019

Micro & Optical Tech Letters

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We investigate the THz current oscillations in resonant tunneling diodes (RTD) oscillators with the transient drift‐diffusion model. The oscillation frequencies have a strong dependence on the biased voltage and doping concentration. With proper biased voltage and doping concentration, the high frequency up to THz can be obtained. The simulations are helpful to deepen the understanding of physical mechanism and guide to improve the performances of RTDs and RTD oscillators. The investigations make RTDs promising candidates as THz sources at room temperature.

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“…[8][9][10] However, the demonstration of resonant tunneling in III-nitrides remained a challenge until recently. [20][21][22][23][24] Several motivations exist to grow RTD on sapphire substrates. [11][12][13][14][15][16][17][18][19] Demonstrations of clear and repeatable NDR from resonant tunneling in III-nitride based RTDs have been limited to those grown on high quality freestanding (FS) GaN substrates, i.e., through homoepitaxy, with either lowaluminum content AlGaN barriers measured at cryogenic temperature, or AlN barriers measured at room temperature.…”

mentioning

confidence: 99%

Repeatable Room Temperature Negative Differential Resistance in AlN/GaN Resonant Tunneling Diodes Grown on Sapphire

Wang

Chen

et al. 2018

Adv Elect Materials

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material systems such as wide tunable direct bandgap, inherent fast carrier dynamics, fast carrier transport, high breakdown fields, robust antiirradiation, and strong chemical stability, RTDs based on III-nitride are expected to provide better tunability of resonant tunneling compared with conventional material platforms such as AlGaInAs and AlGaInSb. [1][2][3][4][5][6] Besides, III-nitride materials are characterized by their large longitudinal optical (LO) phonon energies, making them promising candidates for room temperature terahertz quantum cascade lasers (THz-QCLs). [7] As the simplest quantum device adopting resonant tunneling, RTDs form the fundamental background to understand the quantum confinement and vertical transport processes in nitride-based supperlattices, an essential forestep for the realization of III-nitride-based THz-QCLs and quantum cascade detectors. [8][9][10] However, the demonstration of resonant tunneling in III-nitrides remained a challenge until recently. Due to high dislocation densities in heteroepitaxial GaN templates/buffer layers, current-voltage (I-V) behaviors in earlier reports exhibited noteworthy impact from trap states depending on scan directions and times, where the occurrences of negative differential resistance (NDR) were accidental, irreproducible and could not be easily correlated with resonant tunneling. [11][12][13][14][15][16][17][18][19] Demonstrations of clear and repeatable NDR from resonant tunneling in III-nitride based RTDs have been limited to those grown on high quality freestanding (FS) GaN substrates, i.e., through homoepitaxy, with either lowaluminum content AlGaN barriers measured at cryogenic temperature, or AlN barriers measured at room temperature. [20][21][22][23][24] Several motivations exist to grow RTD on sapphire substrates. First, sapphire substrates are more cost-friendly and easier to realize large-size wafer as well as mass production, and could directly lead to a monolithic integration of RTDs with the increasingly sophisticated high frequency devices fabricated on sapphire and even silicon substrates. Second, unlike FS GaN substrates which are usually n-type without intentionally doping, sapphire substrates are inherently insulating, very Resonant tunneling diodes (RTDs) are candidates for high power terahertz oscillators, and form the basis for understanding the quantum confinement and vertical transport in quantum structures such as quantum cascade lasers and quantum cascade detectors. In this work, repeatable negative differential resistance (NDR) is achieved in AlN/GaN RTDs grown on sapphire substrate by plasma-assisted molecular-beam epitaxy. Two reproducible NDR regions sequentially following two preresonance replicas are demonstrated at room temperature. A current region exhibiting negative correlation with temperature and oscillation-like features is first identified under reverse bias, which is interpreted as a combined contribution of weak resonant tunneling channels through different bound states in the well. The revealed peak...

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Room temperature microwave oscillations in GaN/AlN resonant tunneling diodes with peak current densities up to 220 kA/cm2

Abstract: We report the generation of room temperature microwave oscillations from GaN/AlN resonant 103101-2 Encomendero et al.

Cited by 57 publications

References 36 publications

Theoretical Modeling of Triple‐Barrier Resonant‐Tunneling Diodes Based on AlGaN/GaN Heterostructures

Theoretical Modeling of Triple‐Barrier Resonant‐Tunneling Diodes Based on AlGaN/GaN Heterostructures

Oscillations up to terahertz frequency in resonant tunneling diodes

Repeatable Room Temperature Negative Differential Resistance in AlN/GaN Resonant Tunneling Diodes Grown on Sapphire

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