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13 pages, 3971 KiB

Open AccessArticle

Charge Trapping and Emission during Bias Temperature Stressing of Schottky Gate GaN-on-Silicon HEMT Structures Targeting RF/mm Wave Power Amplifiers

by Barry O’Sullivan, Aarti Rathi, Alireza Alian, Sachin Yadav, Hao Yu, Arturo Sibaja-Hernandez, Uthayasankaran Peralagu, Bertrand Parvais, Adrian Chasin and Nadine Collaert

Micromachines 2024, 15(8), 951; https://doi.org/10.3390/mi15080951 - 24 Jul 2024

Viewed by 474

Abstract

For operation as power amplifiers in RF applications, high electron mobility transistor (HEMT) structures are subjected to a range of bias conditions, applied at both the gate and drain terminals, as the device is biased from the OFF- to ON-state conditions. The stability [...] Read more.

For operation as power amplifiers in RF applications, high electron mobility transistor (HEMT) structures are subjected to a range of bias conditions, applied at both the gate and drain terminals, as the device is biased from the OFF- to ON-state conditions. The stability of the device threshold voltage (V_t) condition is imperative from a circuit-design perspective and is the focus of this study, where stresses in both the ON and OFF states are explored. We see rapid positive threshold voltage increases under negative bias stress and subsequent recovery (i.e., V_t reduces), whereas conversely, we see a negative V_t shift under positive stress and V_t increase during the subsequent relaxation phase. These effects are correlated with the thickness of the GaN layer and ultimately result from the deep carbon-acceptor levels in the C-GaN back barrier incorporated to screen the buffer between the silicon substrate and the epitaxially grown GaN layer. Methods to mitigate this effect are explored, and the consequences are discussed. Full article

(This article belongs to the Special Issue Reliability Issues in Advanced Transistor Nodes, Second Edition)

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13 pages, 5406 KiB

Open AccessArticle

Independently Accessible Dual-Band Barrier Infrared Detector Using Type-II Superlattices

by Seung-man Park and Christoph H. Grein

Photonics 2024, 11(6), 531; https://doi.org/10.3390/photonics11060531 - 3 Jun 2024

Viewed by 481

Abstract

We report a novel dual-band barrier infrared detector (DBIRD) design using InAs/GaSb type-II superlattices (T2SLs). The DBIRD structure consists of back-to-back barrier diodes: a “blue channel” (BC) diode which has an nBp architecture, an n-type layer of a larger bandgap for absorbing the [...] Read more.

We report a novel dual-band barrier infrared detector (DBIRD) design using InAs/GaSb type-II superlattices (T2SLs). The DBIRD structure consists of back-to-back barrier diodes: a “blue channel” (BC) diode which has an nBp architecture, an n-type layer of a larger bandgap for absorbing the blue band infrared/barrier/p-type layer, and a “red channel” (RC) diode which has a pBn architecture, a p-type layer of a smaller bandgap for absorbing the red band infrared/barrier/n-type layer. Each has a unipolar barrier using a T2SL lattice matched to a GaSb substrate to impede the flow of majority carriers from the absorbing layer. Each channel in the DBIRD can be independently accessed with a low bias voltage as is preferable for high-speed thermal imaging. The device modeling of DBIRDs and simulation results of the current–voltage characteristics under dark and illuminated conditions are also presented. They predict that the dual-band operation of the DBIRD will produce low dark currents and 45–56% quantum efficiencies for the in-band photons in the BC with

λ_{c}

= 5.58 μm, and a nearly constant 32% in the RC with

λ_{c}

= 8.05 μm. The spectral quantum efficiency of the BC for 500 K blackbody radiation is approximately 50% over the range of

λ

= 3–4.7 μm, while that of the RC has a peak of 42% at 5.9 μm. The DBIRD may provide improved high-speed dual-band imaging in comparison with NBn dual-band detectors. Full article

(This article belongs to the Section Optoelectronics and Optical Materials)

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10 pages, 9365 KiB

Open AccessFeature PaperMore Editor’s choice articles in journal Micromachines.">Editor’s ChoiceArticle

Non-Buffer Epi-AlGaN/GaN on SiC for High-Performance Depletion-Mode MIS-HEMTs Fabrication

by Penghao Zhang, Luyu Wang, Kaiyue Zhu, Qiang Wang, Maolin Pan, Ziqiang Huang, Yannan Yang, Xinling Xie, Hai Huang, Xin Hu, Saisheng Xu, Min Xu, Chen Wang, Chunlei Wu and David Wei Zhang

Micromachines 2023, 14(8), 1523; https://doi.org/10.3390/mi14081523 - 29 Jul 2023

Viewed by 1227

Abstract

A systematic study of epi-AlGaN/GaN on a SiC substrate was conducted through a comprehensive analysis of material properties and device performance. In this novel epitaxial design, an AlGaN/GaN channel layer was grown directly on the AlN nucleation layer, without the conventional doped thick [...] Read more.

A systematic study of epi-AlGaN/GaN on a SiC substrate was conducted through a comprehensive analysis of material properties and device performance. In this novel epitaxial design, an AlGaN/GaN channel layer was grown directly on the AlN nucleation layer, without the conventional doped thick buffer layer. Compared to the conventional epi-structures on the SiC and Si substrates, the non-buffer epi-AlGaN/GaN structure had a better crystalline quality and surface morphology, with reliable control of growth stress. Hall measurements showed that the novel structure exhibited comparable transport properties to the conventional epi-structure on the SiC substrate, regardless of the buffer layer. Furthermore, almost unchanged carrier distribution from room temperature to 150 °C indicated excellent two-dimensional electron gas (2DEG) confinement due to the pulling effect of the conduction band from the nucleation layer as a back-barrier. High-performance depletion-mode MIS-HEMTs were demonstrated with on-resistance of 5.84 Ω·mm and an output current of 1002 mA/mm. The dynamic characteristics showed a much smaller decrease in the saturation current (only ~7%), with a quiescent drain bias of 40 V, which was strong evidence of less electron trapping owing to the high-quality non-buffer AlGaN/GaN epitaxial growth. Full article

(This article belongs to the Special Issue Advanced Micro- and Nano-Manufacturing Technologies)

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13 pages, 3102 KiB

Open AccessArticle

Thickness Study of Ga₂O₃ Barrier Layer in p-Si/n-MgZnO:Er/Ga₂O₃/ZnO:In Diode

by Shih-Wei Ying, Shou-Yen Chao, Ming-Chang Shih, Chien-Jung Huang and Wen-How Lan

Crystals 2023, 13(2), 275; https://doi.org/10.3390/cryst13020275 - 5 Feb 2023

Viewed by 1378

Abstract

The p-Si/n-MgZnO:Er/Ga₂O₃/ZnO:In diodes with different Ga₂O₃ thicknesses were fabricated through spray pyrolysis deposition at 450 °C with aqueous solutions containing magnesium nitrate, zinc acetate, erbium acetate, gallium nitrate, and indium nitrate precursors. The effects of Ga [...] Read more.

The p-Si/n-MgZnO:Er/Ga₂O₃/ZnO:In diodes with different Ga₂O₃ thicknesses were fabricated through spray pyrolysis deposition at 450 °C with aqueous solutions containing magnesium nitrate, zinc acetate, erbium acetate, gallium nitrate, and indium nitrate precursors. The effects of Ga₂O₃ layer thickness on the diode properties were investigated. For the deposited films, a combined tiny hexagonal slices and small blocks surface morphology was characterized by scanning electron microscopy for all samples. Diodes were formed after In and Ag deposition on the back side and top side, respectively. The current-voltage characteristics and luminescence spectra are studied. With the increasing of Ga₂O₃ thickness, the diode forward bias resistance increases while the reverse biased dark current shows the decrease-increase characters. The Er ion corresponded green light emission was characterized for the diode under reverse biased breakdown condition. The increased luminescent intensity with low turn-on current behaviors was characterized by the diode with a Ga₂O₃ thickness of 4.9 nm. With the diode electrical and luminescence analysis, the effect of the Ga₂O₃ barrier layer on the diode was discussed. The Ga₂O₃ barrier layer improves performance for rare earth-related light-emitting devices. Full article

(This article belongs to the Special Issue Optoelectronics and Photonics in Crystals)

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7 pages, 2393 KiB

Open AccessArticle

Low Trapping Effects and High Electron Confinement in Short AlN/GaN-On-SiC HEMTs by Means of a Thin AlGaN Back Barrier

by Kathia Harrouche, Srisaran Venkatachalam, Lyes Ben-Hammou, François Grandpierron, Etienne Okada and Farid Medjdoub

Micromachines 2023, 14(2), 291; https://doi.org/10.3390/mi14020291 - 22 Jan 2023

Cited by 7 | Viewed by 2739

Abstract

In this paper, we report on an enhancement of mm-wave power performances with a vertically scaled AlN/GaN heterostructure. An AlGaN back barrier is introduced underneath a non-intentionally doped GaN channel layer, enabling the prevention of punch-through effects and related drain leakage current under [...] Read more.

In this paper, we report on an enhancement of mm-wave power performances with a vertically scaled AlN/GaN heterostructure. An AlGaN back barrier is introduced underneath a non-intentionally doped GaN channel layer, enabling the prevention of punch-through effects and related drain leakage current under a high electric field while using a moderate carbon concentration into the buffer. By carefully tuning the Al concentration into the back barrier layer, the optimized heterostructure offers a unique combination of electron confinement and low trapping effects up to high drain bias for a gate length as short as 100 nm. Consequently, pulsed (CW) Load-Pull measurements at 40 GHz revealed outstanding performances with a record power-added efficiency of 70% (66%) under high output power density at V_DS = 20 V. These results demonstrate the interest of this approach for future millimeter-wave applications. Full article

(This article belongs to the Special Issue Wide Bandgap Based Devices: Design, Fabrication and Applications, Volume III)

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7 pages, 615 KiB

Open AccessArticle

Investigation of ON-State Breakdown Mechanism in AlGaN/GaN HEMTs with AlGaN Back Barrier

by Yuchen Li, Sen Huang, Xinhua Wang, Qimeng Jiang and Xinyu Liu

Electronics 2022, 11(9), 1331; https://doi.org/10.3390/electronics11091331 - 22 Apr 2022

Cited by 5 | Viewed by 1465

Abstract

The temperature-dependent ON-state breakdown

B V_{O N}

loci of AlGaN/GaN high-electron-mobility transistors (HEMTs) with an AlGaN back barrier were investigated using the gate current extraction technique. The impact ionization of acceptor-like traps was revealed to be responsible for the ON-state breakdown in [...] Read more.

The temperature-dependent ON-state breakdown

B V_{O N}

loci of AlGaN/GaN high-electron-mobility transistors (HEMTs) with an AlGaN back barrier were investigated using the gate current extraction technique. The impact ionization of acceptor-like traps was revealed to be responsible for the ON-state breakdown in HEMTs as a 2D electron gas (2DEG) channel is marginally turned on. The characteristic electric field

E_{i}

of impact ionization was extracted, exhibiting a U-shaped temperature dependence from 40 to −30

^{\circ}

C, with minimum

E_{i}

occurring at −10

^{\circ}

C. The impurity scattering effect of acceptor-like traps in AlGaN/GaN heterostructures is suggested to be responsible for the negative temperature dependence of

B V_{O N}

and

E_{i}

below −10

^{\circ}

C. Full article

(This article belongs to the Section Semiconductor Devices)

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9 pages, 2392 KiB

Open AccessArticle

Plasma-Enhanced Atomic Layer Deposition of TiN Thin Films as an Effective Se Diffusion Barrier for CIGS Solar Cells

by Hyun-Jae Woo, Woo-Jae Lee, Eun-Kyong Koh, Seung Il Jang, Shinho Kim, Hyoungseok Moon and Se-Hun Kwon

Nanomaterials 2021, 11(2), 370; https://doi.org/10.3390/nano11020370 - 2 Feb 2021

Cited by 6 | Viewed by 3123

Abstract

Plasma-enhanced atomic layer deposition (PEALD) of TiN thin films were investigated as an effective Se diffusion barrier layer for Cu (In, Ga) Se₂ (CIGS) solar cells. Before the deposition of TiN thin film on CIGS solar cells, a saturated growth rate of [...] Read more.

Plasma-enhanced atomic layer deposition (PEALD) of TiN thin films were investigated as an effective Se diffusion barrier layer for Cu (In, Ga) Se₂ (CIGS) solar cells. Before the deposition of TiN thin film on CIGS solar cells, a saturated growth rate of 0.67 Å/cycle was confirmed using tetrakis(dimethylamido)titanium (TDMAT) and N₂ plasma at 200 °C. Then, a Mo (≈30 nm)/PEALD-TiN (≈5 nm)/Mo (≈600 nm) back contact stack was fabricated to investigate the effects of PEALD-TiN thin films on the Se diffusion. After the selenization process, it was revealed that ≈5 nm-thick TiN thin films can effectively block Se diffusion and that only the top Mo layer prepared on the TiN thin films reacted with Se to form a MoSe₂ layer. Without the TiN diffusion barrier layer, however, Se continuously diffused along the grain boundaries of the entire Mo back contact electrode. Finally, the adoption of a TiN diffusion barrier layer improved the photovoltaic efficiency of the CIGS solar cell by approximately 10%. Full article

(This article belongs to the Special Issue Nanomaterials for Energy Conversion and Catalytic Applications)

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7 pages, 3790 KiB

Open AccessArticle

The Characteristics of 6-Inch GaN on Si RF HEMT with High Isolation Composited Buffer Layer Design

by Chong-Rong Huang, Chia-Hao Liu, Hsiang-Chun Wang, Hsuan-Ling Kao, Hsien-Chin Chiu, Chih-Tien Chen and Kuo-Jen Chang

Electronics 2021, 10(1), 46; https://doi.org/10.3390/electronics10010046 - 30 Dec 2020

Cited by 5 | Viewed by 2616

Abstract

In this study, a 50-nm Al_0.05Ga_0.95N back barrier (BB) layer was used in an AlGaN/GaN high-electron-mobility transistor between the two-dimensional electron gas channel and Fe-doped/C-doped buffer layers. This BB layer can reduce the channel layer. The BB layer is [...] Read more.

In this study, a 50-nm Al_0.05Ga_0.95N back barrier (BB) layer was used in an AlGaN/GaN high-electron-mobility transistor between the two-dimensional electron gas channel and Fe-doped/C-doped buffer layers. This BB layer can reduce the channel layer. The BB layer is affected by doped carriers in the buffer layer and the conduction energy band between the channel and the buffer layers. The I_on/I_off ratio of the BB device was 4.66 × 10⁵, and the ratio for the device without BB was 1.91 × 10³. Lower leakage currents were obtained in the BB device because of the higher conduction energy band. The 0.25-μm gate length device with the BB exhibited a high current gain cutoff frequency of 24.4 GHz, and power gain cutoff frequency of 73 GHz. Full article

(This article belongs to the Section Microelectronics)

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