| 1. |
- Castillo, Ragnar Ferrand Drake Del, et al.
(författare)
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Characterization of Trapping Effects Related to Carbon Doping Level in AlGaN Back-Barriers for AlGaN/GaN HEMTs
- 2024
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646. ; , s. 0-1
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Tidskriftsartikel (refereegranskat)abstract
- The impact of different carbon concentrations in the Al 0.06 Ga 0.94 N graded back-barrier and GaN buffer of high electron mobility transistors (HEMTs) is investigated. Four epi-wafers with different carbon concentrations, ranging from 1 × 10 17 to 5 × 10 17 cm −3 , were grown by metal organic chemical vapor deposition (MOCVD). HEMTs with 100 and 200 nm gate lengths were fabricated and characterized with dc, Pulsed-IV, drain current transient spectroscopy (DCTS), and large-signal measurements at 30 GHz. It is shown that the back-barrier effectively prevents buffer-related electron trapping. The highest C-doping provides the best 2DEG confinement, while lower carbon doping levels are beneficial for a high output power and efficiency. A C-doping of 1 × 10 17 cm −3 offers the highest output power at maximum power added efficiency (PAE) (1.8 W/mm), whereas 3 × 10 17 cm −3 doping provides the highest PAE ( > 40%). The C-profiles acquired by using secondary ion mass spectroscopy (SIMS), in combination with DCTS, is used to explain the electron trapping effects. Traps associated with the C-doping in the back-barrier are identified and the bias ranges for the trap activation are discussed. The study shows the importance of considering the C-doping level in the back-barrier of microwave GaN HEMTs for power amplification and generation.
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| 2. |
- Del Castillo, Ragnar Ferrand-Drake, et al.
(författare)
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Characterization of Trapping Effects Related to Carbon Doping Level in AlGaN Back-Barriers for AlGaN/GaN HEMTs
- 2024
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 0018-9383 .- 1557-9646.
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Tidskriftsartikel (refereegranskat)abstract
- The impact of different carbon concentrations in the Al 0.06 Ga 0.94 N graded back-barrier and GaN buffer of high electron mobility transistors (HEMTs) is investigated. Four epi-wafers with different carbon concentrations, ranging from 1 x 10(17) to 5 x 10(17) cm( -3) , were grown by metal organic chemical vapor deposition (MOCVD). HEMTs with 100 and 200 nm gate lengths were fabricated and characterized with dc, Pulsed-IV, drain current transient spectroscopy (DCTS), and large-signal measurements at 30 GHz. It is shown that the back-barrier effectively prevents buffer-related electron trapping. The highest C-doping provides the best 2DEG confinement, while lower carbon doping levels are beneficial for a high output power and efficiency. A C-doping of 1 x 10(17)cm( -3) offers the highest output power at maximum power added efficiency (PAE) (1.8 W/mm), whereas 3 x 10(17) cm( -3) doping provides the highest PAE ( > 40%). The C-profiles acquired by using secondary ion mass spectroscopy (SIMS), in combination with DCTS, is used to explain the electron trapping effects. Traps associated with the C-doping in the back-barrier are identified and the bias ranges for the trap activation are discussed. The study shows the importance of considering the C-doping level in the back-barrier of microwave GaN HEMTs for power amplification and generation.
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| 3. |
- Ferrand-Drake Del Castillo, Ragnar, 1993, et al.
(författare)
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Characterization of Trapping Effects Related to Carbon Doping Level in AlGaN Back-Barriers for AlGaN/GaN HEMTs
- 2024
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1557-9646 .- 0018-9383. ; 71:6, s. 3596-3602
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Tidskriftsartikel (refereegranskat)abstract
- The impact of different carbon concentrations in the Al Ga N graded back-barrier and GaN buffer of high electron mobility transistors (HEMTs) is investigated. Four epi-wafers with different carbon concentrations, ranging from 1 10 to 5 10 cm , were grown by metal organic chemical vapor deposition (MOCVD). HEMTs with 100 and 200 nm gate lengths were fabricated and characterized with dc, Pulsed-IV, drain current transient spectroscopy (DCTS), and large-signal measurements at 30 GHz. It is shown that the back-barrier effectively prevents buffer-related electron trapping. The highest C-doping provides the best 2DEG confinement, while lower carbon doping levels are beneficial for a high output power and efficiency. A C-doping of 1 10 cm offers the highest output power at maximum power added efficiency (PAE) (1.8 W/mm), whereas 3 10 cm doping provides the highest PAE ( 40%). The C-profiles acquired by using secondary ion mass spectroscopy (SIMS), in combination with DCTS, is used to explain the electron trapping effects. Traps associated with the C-doping in the back-barrier are identified and the bias ranges for the trap activation are discussed. The study shows the importance of considering the C-doping level in the back-barrier of microwave GaN HEMTs for power amplification and generation.
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| 4. |
- Ferrand-Drake Del Castillo, Ragnar, 1993, et al.
(författare)
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Considerations in the development of a gate process module for ultra-scaled GaN HEMTs
- 2022
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Ingår i: 2022 Compound Semiconductor Week, CSW 2022.
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Konferensbidrag (refereegranskat)abstract
- With the overarching goal of attaining mm-wave GaN High Electron Mobility Transistors (HEMTs), vertical and lateral downscaling is of essence. Utilizing Passivation first technology (coupled with mini-FP T-gates), Schottky Gate (SG) is formed by Fluorine plasma etching, where the plasma etching allows highly defined nanoscale gate-length (Lg) features. However, it damages the crystalline structure of the top barrier layer and leads to Fluorine implantation with ramifications on the sheet carrier density(ns), mobility (μ) and threshold-voltage (VTH) shift towards enhancement mode. In this study, CF4 or NF3 etching with varying over etch times are implemented, with high temperature annealing (600-800°C) post gate recess etching to repair crystal structure damages caused by the etch process.
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| 5. |
- Mebarki, Mohamed Aniss, 1993, et al.
(författare)
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A Cryogenic Scalable Small-Signal & Noise Model of GaN HEMTs
- 2022
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a detailed study of a scalable small signal and noise model at the cryogenic temperature of ~10 K of Gallium Nitride (GaN) - based High Electron Mobility Transistors (HEMTs). The results confirm a clear potential of the GaN technology for the cryogenic low noise applications as the model predicts a minimum noise temperature of ~ 4 K at the physical temperature of ~ 10 K. The improvement of the noise cryogenic performances is attributed to the decrease of the access resistances and the enhancement of the electron transport mechanisms. Moreover, the scalability of the model over the measured different gate peripheries is explored and provides new insights on the possibilities of further optimization of this technology for the cryogenic and low noise operation. Potentially, GaN HEMTs would provide enhanced dynamic range with the noise performance similar to InP devices.
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| 6. |
- Mebarki, Mohamed Aniss, 1993, et al.
(författare)
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A Cryogenic Scalable Small-Signal & Noise Model of GaN HEMTs
- 2023
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Ingår i: Proceedings of the 32nd IEEE International Symposium on Space THz Technology.
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Konferensbidrag (refereegranskat)abstract
- We present a detailed study of a scalable small signal and noise model at the cryogenic temperature of ~10 K of Gallium Nitride (GaN) - based High Electron Mobility Transistors (HEMTs). The results confirm a clear potential of the GaN technology for the cryogenic low noise applications as the model predicts a minimum noise temperature of ~ 4 K at the physical temperature of ~ 10 K. The improvement of the noise cryogenic performances is attributed to the decrease of the access resistances and the enhancement of the electron transport mechanisms. Moreover, the scalability of the model over the measured different gate peripheries is explored and provides new insights on the possibilities of further optimization of this technology for the cryogenic and low noise operation. Potentially, GaN HEMTs would provide enhanced dynamic range with the noise performance similar to InP devices.
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| 7. |
- Mebarki, Mohamed Aniss, 1993, et al.
(författare)
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Comparison of the low noise performance of GaN HEMTs and MIS-HEMTs at cryogenic temperatures
- 2023
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Ingår i: 2023 18th European Microwave Integrated Circuits Conference, EuMIC 2023. ; , s. 29-32
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Konferensbidrag (refereegranskat)abstract
- This work presents the comparison of the noise performance of AlGaN/GaN MIS-HEMTs and HEMTs at cryogenic temperatures. Wideband noise measurements at a physical temperature of 4K were performed in order to extract the noise characteristics of the devices, within the range of frequencies of 3-7 GHz. A DC and RF characterization of the devices are also presented to further assess their cryogenic performances. Over the measured frequency band, the results indicate that both technologies are able to present an average best noise temperature as low as 8 K. The MIS-HEMT presents a slight advantage at low bias condition, mainly due to its reduced gate capacitance. The presented results are the first report on the microwave low-noise performance of cryogenic GaN MIS-HEMT, and constitute their current state-of the art.
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| 8. |
- Mebarki, Mohamed Aniss, 1993, et al.
(författare)
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GaN HEMT with superconducting Nb gates for low noise cryogenic applications
- 2022
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Ingår i: 2022 Compound Semiconductor Week, CSW 2022.
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Konferensbidrag (refereegranskat)abstract
- We report on the successful integration of superconducting Nb gate electrodes to AlGaN/GaN heterostructures and HEMTs for low noise cryogenic applications. First, a specific Nb-gate process was developed and implemented on stand-alone gate test structures. The latter were tested at cryogenic temperatures down to 4 K, using DC end-to-end measurements. The results show a clear transition to a superconducting state at Tc ~ 9.2 K. The superconducting nature of the Nb gates further verified on actual HEMTs, featuring 2 fingers design with gate length of 0.2 μm, through their S-parameters measurements at T
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| 9. |
- Mebarki, Mohamed Aniss, 1993, et al.
(författare)
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GaN High-Electron-Mobility Transistors with Superconducting Nb Gates for Low-Noise Cryogenic Applications
- 2023
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Ingår i: Physica Status Solidi (A) Applications and Materials Science. - : Wiley. - 1862-6319 .- 1862-6300. ; 220:8
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Tidskriftsartikel (refereegranskat)abstract
- The successful integration of superconducting niobium (Nb) gate electrodes into cryogenic gallium nitride (GaN)-based high-electron-mobility transistors (HEMTs) is reported. This is achieved through a specifically developed microfabrication process. The device's DC, microwave, and noise performances at cryogenic temperatures, down to 4 K, are studied and presented. The superconductivity of the gate is tested using DC end-to-end measurements. A clear superconducting state transition at a critical temperature, Tc, of ≈9.2 K is shown. This is further verified with GaN HEMTs with two gate fingers and a gate length of 0.2 μm, through the extraction and validation of a small-signal model at T < Tc. Additionally, the superconductivity of the gate is verified for several gate widths and lengths, showing a significant reduction of the gate resistance independently of its dimensions. Finally, a comparative study of the cryogenic microwave noise performances of the GaN HEMTs with gold (Au) and Nb gates is presented. The Au-gated device presents a competitive optimum noise temperature, Tmin-opt, of ≈8 K at 5 GHz, demonstrating the potential of this technology for cryogenic low-noise applications. The Nb-gated device presents a 5 K higher Tmin-opt, which is found to be related to the suppression of the superconductivity of the Nb gate at the optimum-noise bias.
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| 10. |
- Mebarki, Mohamed Aniss, 1993, et al.
(författare)
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Noise Characterization and Modeling of GaN-HEMTs at Cryogenic Temperatures
- 2023
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Ingår i: IEEE Transactions on Microwave Theory and Techniques. - 0018-9480 .- 1557-9670. ; 71:5, s. 1923-1931
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Tidskriftsartikel (refereegranskat)abstract
- We report on the noise characterization and modeling of AlGaN/GaN high-electron-mobility transistors (HEMTs) at a cryogenic temperature (CT) of ∼ 10 K within the frequency range of 4.5–6.5 GHz. This work is the first model in the literature describing the high-frequency noise behavior of GaN-based HEMTs at CTs using a two-parameter-noise concept. The suggested model, which is based on measured noise figures and scattering parameters, provides the frequency and the bias dependence of the cryogenic noise properties of AlGaN/GaN HEMTs. The noise contributions from the intrinsic device, the parasitic network, and the gate leakage are separately extracted. The contribution of the access network is found in the order of 1 K and increases with the frequency, while the gate leakage has an impact of the order of 0.1 K and increases at low frequency. The model provides a basis for the future design and implementation of GaN-based cryogenic low-noise amplifiers.
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