Dispersive Effects in Microwave AlGaN/AlN/GaN HEMTs With Carbon-Doped Buffer

Gustafsson, Sebastian; Chen, Jr-Tai; Bergsten, Johan; Forsberg, Urban; Thorsell, Mattias; Janzén, Erik; Rorsman, Niklas

doi:10.1109/ted.2015.2428613

Cited by 65 publications

(27 citation statements)

References 29 publications

(29 reference statements)

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“…The pinch‐off voltage of the GaN‐on‐SiC is −4 V; while its value for the GaN‐on‐Si is equal to −3 V. The higher traps induced back‐gating for the GaN‐on‐Si reduces the required negative voltage to pinch‐off the channel. This has been also reported in Reference , which showed that higher concentration of the buffer traps will shift up the pinch‐off voltage. The impact of higher trapping in GaN‐on‐Si with respect to GaN‐on‐Dia has been also reported in Reference and summarized in Table .…”

Section: Simulation and Measurement Resultssupporting

confidence: 79%

“…As can be seen, the GaN‐on‐Si device shows lower current levels with respect to the GaN‐on‐SiC. Also the effect of back‐gating potential due to buffer traps is clear from the different pinch‐off voltages of these devices. The pinch‐off voltage of the GaN‐on‐SiC is −4 V; while its value for the GaN‐on‐Si is equal to −3 V. The higher traps induced back‐gating for the GaN‐on‐Si reduces the required negative voltage to pinch‐off the channel.…”

Section: Simulation and Measurement Resultsmentioning

confidence: 89%

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On the performance of GaN‐on‐Silicon, Silicon‐Carbide, and Diamond substrates

Jarndal

Arivazhagan

Nirmal

2020

Int J RF Microw Comput Aided Eng

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In this article, threading dislocations and its impact on the electrical and thermal performance of GaN-on-Diamond (Dia), -SiC, and -Si high electron mobility transistor (HEMT) has been investigated. TCAD simulation of GaN-HEMT is performed with various buffer traps to mimic the lattice mismatch/dislocation density at GaN/Si, GaN/SiC, and GaN/Dia interface. It has been found that, the dislocations not only induce traps, but also degrade the thermal conductivity of the GaN-buffer. This accordingly could deteriorate the thermal characteristic of GaN-on-Dia, which has higher lattice mismatch with respect to GaN-on-SiC. This investigation showed that the growth process of GaN-on-Dia should be optimized in order to reduce the threading dislocations. This accordingly could dramatically further improve its outstanding thermal characteristics with respect to GaN-on-SiC and GaN-on-Si devices. K E Y W O R D S diamond and silicon carbide, GaN, HEMT, silicon, substrate

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Section: Simulation and Measurement Resultssupporting

confidence: 79%

Section: Simulation and Measurement Resultsmentioning

confidence: 89%

On the performance of GaN‐on‐Silicon, Silicon‐Carbide, and Diamond substrates

Jarndal

Arivazhagan

Nirmal

2020

Int J RF Microw Comput Aided Eng

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“…It was demonstrated that the carbon profile could be tuned so that the trap density close to the two-dimensional electron gas (2DEG) was reduced, while still demonstrating HEMTs with low leakage currents and small dispersive effects. 8 However, the growth process tuning involved changes in growth temperature, which can result in poor epitaxial layer uniformity and structural quality, as well as particle down falls during temperature transition.…”

Section: à3mentioning

confidence: 99%

“…It is clear that when an optimized process window for GaN is used during growth of the entire carbon doped buffer layer, the structural quality exceeds that when process tuning is used. 8 This allows the use of a gaseous carbon source even for very high carbon doping. The rocking curve of the AlN (0002) reflection has a FWHM value of 240 arcsec.…”

Section: à3mentioning

confidence: 99%

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Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results

Bergsten

Nilsson

et al. 2015

Applied Physics Letters

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The creation of a semi insulating (SI) buffer layer in AlGaN/GaN High Electron Mobility Transistor (HEMT) devices is crucial for preventing a current path beneath the two-dimensional electron gas (2DEG). In this investigation, we evaluate the use of a gaseous carbon gas precursor, propane, for creating a SI GaN buffer layer in a HEMT structure. The carbon doped profile, using propane gas, is a two stepped profile with a high carbon doping (1.5 × 1018 cm−3) epitaxial layer closest to the substrate and a lower doped layer (3 × 1016 cm−3) closest to the 2DEG channel. Secondary Ion Mass Spectrometry measurement shows a uniform incorporation versus depth, and no memory effect from carbon doping can be seen. The high carbon doping (1.5 × 1018 cm−3) does not influence the surface morphology, and a roughness root-mean-square value of 0.43 nm is obtained from Atomic Force Microscopy. High resolution X-ray diffraction measurements show very sharp peaks and no structural degradation can be seen related to the heavy carbon doped layer. HEMTs are fabricated and show an extremely low drain induced barrier lowering value of 0.1 mV/V, demonstrating an excellent buffer isolation. The carbon doped GaN buffer layer using propane gas is compared to samples using carbon from the trimethylgallium molecule, showing equally low leakage currents, demonstrating the capability of growing highly resistive buffer layers using a gaseous carbon source.

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Effect of Fe Doping Profile on Current Collapse in GaN‐based RF HEMTs

Xu,

Guo,

Tao

et al. 2024

Chemistry A European J

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Using computer‐aided design (TCAD) simulation, the impact of the Fe doping profile, including concentration, decay rate, and depth of the doping region on current‐collapse magnitude (∆CC) in 0.5‐μm gated GaN‐based high electron mobility transistors (HEMTs) is systematically investigated. Accurate simulation models are established and developed to facilitate the fabrication of electronics. It is elucidated that the intricate interplay between trapping and de‐trapping of Fe‐related traps at the gate‐drain edge is responsible for current collapse. The concentration and decay rate of the doping region have a more significant impact on current collapse than the depth. Increased trap state density near two‐dimensional electron gas (2DEG) channel caused by deep‐level acceptors would boost ∆CC. However, a minor dynamic reduction in 2DEG density (nT) induces a relatively small ∆CC. By adjusting the concentration, decay rate, and depth of the doping region, ∆CC of GaN‐based Radio Frequency (RF) HEMTs can be reduced by approximately 50.3%.The optimized distribution of Fe doping discussed in this work helps to prepare GaN‐based RF HEMTs with a limited current collapse effect.

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Dispersive Effects in Microwave AlGaN/AlN/GaN HEMTs With Carbon-Doped Buffer

Cited by 65 publications

References 29 publications

On the performance of GaN‐on‐Silicon, Silicon‐Carbide, and Diamond substrates

On the performance of GaN‐on‐Silicon, Silicon‐Carbide, and Diamond substrates

Carbon doped GaN buffer layer using propane for high electron mobility transistor applications: Growth and device results

Effect of Fe Doping Profile on Current Collapse in GaN‐based RF HEMTs

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