AlGaN/GaN HFETs on Fe‐doped GaN substrates

Oshimura, Yoshinori; Takeda, Kenta; Sugiyama, Tetsuya; Iwaya, Motoaki; Kamiyama, Satoshi; Amano, Hiroshi; Akasaki, Isamu; Bandoh, Akira; Udagawa, T.

doi:10.1002/pssc.200983587

Cited by 13 publications

(14 citation statements)

References 10 publications

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“…19 However, during the growth of HEMT structures, Fe from the GaN:Fe substrates can incorporate into the GaN epilayer making the sheet resistance worse and, thus, affecting device operation. 20 On the other hand, carbon can be a promising alternative dopant for fabrication of SI bulk GaN substrates by the HVPE method, following an example of successful use of C in metal-organic vapor phase epitaxy (MOVPE) growth of SI GaN layers for HEMT structures. 21 Previously, it was found that doping by C during the HVPE growth of GaN results in increase of YL around 2.2 eV.…”

Section: à3mentioning

confidence: 99%

Optical properties of C-doped bulk GaN wafers grown by halide vapor phase epitaxy

Khromov

Hemmingsson

Ḿonemar

et al. 2014

Journal of Applied Physics

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Optical and structural studies of homoepitaxially grown m-plane GaN Appl. Phys. Lett. 100, 172108 (2012) Freestanding bulk C-doped GaN wafers grown by halide vapor phase epitaxy are studied by optical spectroscopy and electron microscopy. Significant changes of the near band gap (NBG) emission as well as an enhancement of yellow luminescence have been found with increasing C doping from 5 Â 10 16 cm À3 to 6 Â 10 17 cm À3. Cathodoluminescence mapping reveals hexagonal domain structures (pits) with high oxygen concentrations formed during the growth. NBG emission within the pits even at high C concentration is dominated by a rather broad line at $3.47 eV typical for n-type GaN. In the area without pits, quenching of the donor bound exciton (DBE) spectrum at moderate C doping levels of 1-2 Â 10 17 cm À3 is observed along with the appearance of two acceptor bound exciton lines typical for Mg-doped GaN. The DBE ionization due to local electric fields in compensated GaN may explain the transformation of the NBG emission. V C 2014 AIP Publishing LLC.

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Section: à3mentioning

confidence: 99%

Optical properties of C-doped bulk GaN wafers grown by halide vapor phase epitaxy

Khromov

Hemmingsson

Ḿonemar

et al. 2014

Journal of Applied Physics

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“…HEMT on the Fe-doped GaN substrate was demonstrated by Oshimura et al [8]. In the present study, in the HEMT structure fabricated on the Fe-doped GaN substrate, it was determined that I DS of HEMT on the Fe-doped GaN substrate deteriorates when the channel layer thickness is insufficient.…”

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confidence: 51%

Characterization of high electron mobility transistor fabricated on hydride vapor phase epitaxy‐grown GaN templates containing various Fe concentrations

Sugimoto

Nishihira

Arita

et al. 2017

Phys. Status Solidi C

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An AlGaN/GaN high electron mobility transistor (HEMT) structure was grown on a semi‐insulating (SI) GaN layer or substrate to suppress a leakage current and achieve a high breakdown voltage. Fe can be used as doping material to obtain SI‐GaN. However, the relationship between the Fe concentration in the GaN layers and its influence on HEMT characteristics has not yet been investigated. In this study, we therefore investigated the influence of Fe concentration in the GaN layers on HEMT characteristics. The GaN layers containing several Fe concentrations were grown by hydride vapor phase epitaxy (HVPE). The Fe concentration was varied from 3 × 1017 to 3 × 1020 atoms cm−3. It was determined that the source‐drain current (IDS) decreased as the Fe concentration increased. In the case of a low Fe concentration of 3 × 1017 atoms cm−3, IDS was almost the same as that of HEMT on the non‐Fe‐doped GaN template. Thus, HEMT characteristics deteriorated as the Fe concentration increased. The channel layer played a role in blocking the adverse effects of Fe doping on the two‐dimensional electron gas concentration in AlGaN/GaN. Moreover, it was shown that the GaN channel layer must become thicker as the Fe concentration of the GaN layers increases.

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“…The local variation in carrier concentration around the Fe 2 O 3 particles can be originated either from the solid phase diffusion of Fe atoms into GaN during the annealing process after the cocatalyst deposition, or by the formation of a junction between GaN and Fe 2 O 3 . Although it has been shown that Fe atoms can diffuse into GaN as far as 1 μm if it is annealed at 1,050 °C 35 , the low temperature of our annealing process (500 °C) and the exponential dependence of the diffusion coefficient on temperature suggest that the doping effect is not considerable. Besides, Fe atoms in GaN act as acceptor-like point defects 36 , decreasing the n-type carrier concentration of GaN.…”

Section: Resultsmentioning

confidence: 83%

Photoelectrochemical and crystalline properties of a GaN photoelectrode loaded with α-Fe2O3 as cocatalyst

Velazquez-Rizo

Ohkawa

2020

Sci Rep

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nitrides are of particular interest in energy applications given their suitability to photocatalytically generate H 2 from aqueous solutions. However, one of the drawbacks of nitrides is the decomposition they suffer when used in photoelectrochemical cells. Here, we report the improvement of the catalytic performance and chemical stability of a Gan electrode when it is decorated with fe 2 o 3 particles compared with an undecorated electrode. our results show a higher reaction rate in the fe 2 o 3 /Gan electrode, and that photocorrosion marks take more than 20 times longer to appear on it. We also characterized the crystalline properties of the fe 2 o 3 particles with transmission electron microscopy. the results show that the fe 2 o 3 particles keep an epitaxial relationship with GaN that follows the fe 2 o 3 {0003}||Gan{0001} and fe 2 o 3 [1120]||Gan[1100] symmetry constraints. We also characterized an fe 2 o 3 (thin film)/GaN electrode, however it did not present any catalytic improvement compared with a bare GaN electrode. The epitaxial relationship found between the Fe 2 o 3 thin film and GaN exhibited the fe 2 o 3 {1120}||Gan{0002} and fe 2 o 3 [3300]||Gan[1120] symmetry constraints. The increasing energy demand of humankind and the negative environmental impact of the consumption of fossil fuels are driving the development of alternative energy sources. One of the candidates to substitute fossil fuels is H 2 , which can generate energy through its direct combustion or in fuel cells without creating pollution. However, the non-pollutant attributes of H 2 have been overshadowed by the lack of an environmentally friendly method for its manufacture. One alternative to sustainably generate H 2 is the photocatalytic water splitting using semiconductors 1. Nitrides have received considerable attention in this field because, as a result of their band gap tunability 2-8 , they can absorb most of the energy of the solar spectrum. After the first demonstration of photoelectrochemical (PEC) H 2 generation using GaN thin films as photoelectrodes 9 , and their subsequent improvement to perform chemical reactions without any external electrical bias 10 , the discovery of the NiO cocatalyst technology 11 greatly boosted the expectations of nitride-based photocatalysts. NiO cocatalyst improved not only the Energy Conversion Efficiency (ECE) of nitride photoelectrodes, but also their lifetime, which has been demonstrated to be at least 500 h 12. It has also been confirmed that NiO/nitride photoelectrodes can be used to generate more complex byproducts than H 2 , such as formic acid and methane from CO 2 in artificial photosynthesis reactions 13-16. The improvement of the catalytic activity of GaN photoanodes by using metals or metal oxides as cocatalysts can be attributed to the introduction of active sites by the metal or oxygen atoms. For example, in water splitting on metal oxides, the Oxygen Evolution Reaction (OER) mechanism has been described conventionally as a four proton-electron transfer reaction in the metal-sites...

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AlGaN/GaN HFETs on Fe‐doped GaN substrates

Cited by 13 publications

References 10 publications

Optical properties of C-doped bulk GaN wafers grown by halide vapor phase epitaxy

Optical properties of C-doped bulk GaN wafers grown by halide vapor phase epitaxy

Characterization of high electron mobility transistor fabricated on hydride vapor phase epitaxy‐grown GaN templates containing various Fe concentrations

Photoelectrochemical and crystalline properties of a GaN photoelectrode loaded with α-Fe2O3 as cocatalyst

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