Realization of high-performance hetero-field-effect-transistor-type ultraviolet photosensors using p-type GaN comprising three-dimensional island crystals

Yamamoto, Yuma; Yoshikawa, Akira; Kusafuka, Toshiki; Okumura, Takamasa; Iwaya, Motoaki; Takeuchi, Tetsuya; Kamiyama, Satoshi; Akasaki, Isamu

doi:10.7567/jjap.55.05fj07

Cited by 5 publications

(6 citation statements)

References 34 publications

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“…This phenomenon arises from optical gain. For AlGaN HEMTs, optical gain is attributed to generation of free holes in the barrier layer, thereby enhancing the 2D electron gas (2DEG) or collection of free carriers generated in the channel layer by the depletion region under the gate [142] . In addition, sub-bandgap absorption by either the barrier or the channel layer has also been observed to produce strong thresholds in photoresponse in AlGaN HEMTs, indicating that deep level defects can function in the photoresponse [143] .…”

Section: Phototransistormentioning

confidence: 99%

Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection

Liu

Zhou

2022

Chin. Opt. Lett.

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Solar-blind ultraviolet photodetectors (SBPDs) have attracted tremendous attention in the environmental, industrial, military, and biological fields. Aluminum gallium nitride (AlGaN), a kind of representative III-nitride semiconductor, has promising prospects in solar-blind photodetection owing to its tunable wide bandgap and industrial feasibility. Considering the high defect density in the AlGaN epilayer directly grown on a sapphire substrate, employing an AlN/sapphire template turns out to be an effective method to achieve a high-quality AlGaN epilayer, thereby enhancing the SBPD performances. In recent years, a variety of remarkable breakthroughs have been achieved in the SBPDs. In this paper, the progress on photovoltaic AlGaN-based SBPDs is reviewed. First, the basic physical properties of AlGaN are introduced. Then, fabrication methods and defect annihilation of the AlN/sapphire template are discussed. Various photovoltaic SBPDs are further summarized, including Schottky barrier, metal-semiconductor-metal, p-n/p-i-n and avalanche photodiodes. Furthermore, surface modification and photoelectrochemical cell techniques are introduced. Benefitting from the development of fabrication techniques and optoelectronic devices, photovoltaic AlGaN photodiodes exhibit a promising prospect in solar-blind ultraviolet photodetection.

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Section: Phototransistormentioning

confidence: 99%

Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection

Liu

Zhou

2022

Chin. Opt. Lett.

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“…By using p-type GaN or Schottky electrode, it is possible to expect a low dark current by forming a depletion layer, resulting in high rejection ratio as a result. [27][28][29] We also reported the result of applying this device structure to photosensor with photosensitivity in visible light region. 25,26) In these reports, the photosensors with photosensitivity of 4 × 10 5 A W −1 at approximately 380 nm, rejection ratio of 17, and absorption wavelength edge of 450 nm were realized by using p-type GaInN gate.…”

mentioning

confidence: 95%

“…[15][16][17][18][19][20] Thus far, we have reported high photosensitivity AlGaN/GaN heterostructure field effect transistor (HFET) type photosensors with p-type GaN optical gate, AlGaN/GaN HFET type photosensor with p-type GaInN optical gate, AlGaN/AlGaN HFET type photosensor with p-type GaN optical gate, and AlGaN/ AlGaN HFET type photosensor with Schottky electrode gate, respectively. [21][22][23][24][25][26][27][28][29] Since these HFET type photosensors have two-dimensional electron gas (2DEG) with high mobility, a large gain is obtained and as a result high photosensitivity is realized. By using p-type GaN or Schottky electrode, it is possible to expect a low dark current by forming a depletion layer, resulting in high rejection ratio as a result.…”

mentioning

confidence: 99%

“…The thickness of p-type GaN layer needs to be more than 20 nm for obtaining high rejection ratio as a result of investigating the AlGaN/ AlGaN HFET type-based UV photosensors with p-type GaN. 28) However, since it is very difficult to obtain high quality p-type such thick GaInN with a high InN molar fraction, it is difficult to realize the detection of longer wavelength light using this structure. Therefore, investigating a different device structure is indispensable for increasing the absorption wavelength edge.…”

mentioning

confidence: 99%

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High photosensitivity AlGaN/GaInN/GaN heterojunction field-effect transistor type visible photosensors

Sakata

Iwaya

Takeuchi

et al. 2019

Jpn. J. Appl. Phys.

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We realized the high-performance AlGaN/GaInN/GaN-based heterostructure field-effect transistor type visible photosensors with high photosensitivity and high rejection ratio. We designed the photosensors including two-dimentional electron gas layer at AlGaN/GaInN/GaN hetero-interface to detect visible light with high photosensitivity. Also, carrier depletion using p-type GaN gate was applied for reduction of the dark current. Furthermore, we realized photosensor with externally low dark current density by applying a C-doped GaN layer as an underlying layer. We found that inserting an unintentionally doped GaN interlayer between the GaInN active layer and the C-doped GaN underlying layer is important for realizing a high-performance photosensors. By employing these device designs, a high photosensitivity of 104 A W−1 at wavelength of 430 nm and high rejection ratio of more than 106 were realized under the irradiation of 100 μW cm−2. The absorption edge wavelength was approximately 480 nm corresponding to the bandgap energy of GaInN active layer. Therefore, this device structure is useful as the visible photosensor with high sensitivity and high rejection ratio.

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“…18,19) Yamamoto et al reported the correlation between the film thickness and surface morphology in the growth of a p-GaN gate in an AlGaN/AlGaN heterostructure field effect transistor sensor using MOVPE. 20) Films of p-GaN with <50 nm thickness have low coverage because of the island growth at the initial stage of GaN growth. At a higher film thickness of ∼100 nm, the islands coalesce to form a flat GaN surface.…”

mentioning

confidence: 99%

Pseudomorphic growth of a thin-GaN layer on the AlN single-crystal substrate using metal organic vapor phase epitaxy

Yoshikawa,

Nagatomi,

Nagase

et al. 2024

Jpn. J. Appl. Phys.

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In this study, a 21 nm thick GaN layer with a single-step terrace surface was pseudomorphically grown on an AlN single-crystal substrate using metal organic vapor phase epitaxy by increasing the growth rate up to 1 μm h−1 at a growth temperature of 850 °C and a reactor pressure of 5 kPa. The growth temperature and rate were found to be the factors dominating the flatness and coverage of the thin-GaN layer, revealing that controlling the degree of Ga migration is crucial. Furthermore, threading dislocations was not observed for the thin-GaN layer, with a flat surface, grown on the AlN substrate.

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Realization of high-performance hetero-field-effect-transistor-type ultraviolet photosensors using p-type GaN comprising three-dimensional island crystals

Cited by 5 publications

References 34 publications

Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection

Progress on photovoltaic AlGaN photodiodes for solar-blind ultraviolet photodetection

High photosensitivity AlGaN/GaInN/GaN heterojunction field-effect transistor type visible photosensors

Pseudomorphic growth of a thin-GaN layer on the AlN single-crystal substrate using metal organic vapor phase epitaxy

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