A review of metal–semiconductor contacts for β-Ga<sub>2</sub>O<sub>3</sub>

Lü, Chao; Ji, Xueqiang; Liu, Zeng; Xu, Yan; Lu, Nianduan; Li, Peigang; Tang, Weihua

doi:10.1088/1361-6463/ac8818

Cited by 15 publications

(12 citation statements)

References 137 publications

(128 reference statements)

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“…As shown in Figure c,d, when irradiated by 254 nm light, Ga 2 O 3 will produce photogenerated carriers and electrons will be excited from the valence band to the conduction band, leaving holes in the valence band. A small part of the holes will move to the Ti/Ga 2 O 3 contact surface and be trapped by defects such as oxygen vacancies on the Ti substrate, resulting in a decrease of the Schottky barrier . The other part of the hole will drift into the electrolyte and oxidize the OH – in the captured electrolyte to OH*(h + + OH – = OH*), while the photogenerated electrons will diffuse to the Ti substrate and reach the Pt electrode through the external circuit to reduce the OH* in the electrolyte to OH – (e – + OH* = OH – ), thereby achieving self-powered detection. , In this work, the Ti sheet not only provides a flexible substrate but also acts as a transport channel for carriers, which can accelerate transport.…”

Section: Resultsmentioning

confidence: 99%

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga₂O₃/Electrolyte Heterojunction with High Stability

Chen,

Han,

Chen

et al. 2023

ACS Appl. Electron. Mater.

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In recent years, Ga 2 O 3 flexible solar-blind ultraviolet photodetectors (UVPDs) are gradually becoming the focus of research and the industry because of their excellent wearability, low manufacturing cost, portability, large area compatibility, and high scalability. However, the crystallization temperature required for high-quality α-phase Ga 2 O 3 films exceeds the heat resistance of most flexible materials, so the growth of Ga 2 O 3 films on flexible substrates is a very big challenge. In this study, a highly ordered α-Ga 2 O 3 nanorod array and flexible solar-blind UV PDs with excellent performance were successfully prepared on a flexible titanium (Ti) substrate at 500 °C by a simple water bath heating method. When irradiated by 254 nm ultraviolet light, the α-phase Ga 2 O 3 flexible photodetector exhibits an excellent self-power optical response at 0 V bias and exhibits excellent photoelectric performance with a responsivity of 15.3 mA/W, a fast rise and fall time of 0.104 and 0.077 s, a photocurrent density of 45.7 μA/cm 2 , and a high detectivity of 13.8 × 10 9 Jones. Bending and repeating experiments demonstrated that the detector had high stability. This study provides a simpler and less expensive method for the preparation of flexible self-powered α-Ga 2 O 3 solar-blind UV photodetectors.

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Section: Resultsmentioning

confidence: 99%

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga₂O₃/Electrolyte Heterojunction with High Stability

Chen,

Han,

Chen

et al. 2023

ACS Appl. Electron. Mater.

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“…As with semiconductor heterojunctions [67,68], the interface plays a particular role in M-S contacts, which in turn influences the detection performance in photodetectors [69]. The M-S contacts in Ga 2 O 3 devices, including the photodetector, Schottky barrier diode, and field-effect transistor, are important components governing the device operation and output signals [70,71]. In general, the M-S contact refers to ohmic and Schottky modality, distinguished by the electrical behavior and choice of the metal electrodes of various work functions that can modulate device performance [72].…”

Section: Advantages and Mechanismsmentioning

confidence: 99%

A review of Ga₂O₃ deep-ultraviolet metal–semiconductor Schottky photodiodes

Liu¹,

Tang²

2023

J. Phys. D: Appl. Phys.

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Deep-ultraviolet (DUV) photodetectors are fundamental building blocks in lots of solid-state DUV optoelectronics, whose prosperity is pinned hope on continuous innovations on semiconductor materials and physics of device structures. Conquering the technological obstacles in narrow bandgap silicon-based optoelectronics (photodetectors and photonics), wide bandgap semiconductor gained a high level of enthusiasm in constructing DUV photodetector, thereinto Ga2O3 is a typical representative benefiting from its promising physical and chemical properties in nature, especially for its energy bandgap around 4.5-5.2 eV for its five phases (α, β, γ, ε and δ). Which just right provides a hard-won opportunity to respond to DUV light irradiation without the need for adjusting the component in compounds and/or adding external optical instruments, as some compound semiconductors AlxGa1-xN, MgxZn1-xO, etc. According to literature reports on Ga2O3-based photodetectors, the device morphology includes metal-semiconductor-metal (MSM) photodetector, homojunction or heterojunction photodetector, phototransistor, and Schottky photodiode. What calls for special attention is that Schottky photodiode with a rectified Schottky junction has certain advantages: easy fabrication, fast photoresponse, less high-temperature diffusion, low dark current, high detectivity, and self-powered operation; in spite of weaknesses of thin depletion layer and low barrier at metal-semiconductor (M-S) interface. Therefore, in this concise literature review article, the recent progresses on Ga2O3-based Schottky photodiodes is discussed in order to show some suggestions on choice of Schottky metal, interfacial barrier modulation, space electric field adjustment, energy band engineering, and photodetection performance improvement, for promoting the further developments of DUV photodetection in the near future.

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“…In Ga 2 O 3 device fabrication, low-resistance Ohmic contacts are crucial. [1][2][3][4][5][6][7][8][9][10][11][12] High contact resistance degrades device switching speeds and exacerbates reliability concerns due to the localized heating generated at the contact interface during current flow in device operation. [2][3][4][5][6][7] Low-resistance Ohmic contacts in Ga 2 O 3 power electronics minimize power dissipation, [1][2][3] while high-resistance contacts result in increased Joule heating.…”

mentioning

confidence: 99%

“…The combined application of RIE and Si ion implantation yielded a specific contact resistance of 8.1 × 10 −6 Ω cm 2 , underscoring the potential for enhancing Ohmic contact properties through the synergistic utilization of these techniques. [1][2][3][4][5][6][7][8][9][10][11] A typical metallization for n-type Ga 2 O 3 Ohmic contacts is Ti/ Au. Ti is chosen for its low work function and robust adhesion to Ga 2 O 3 , while Au possesses low resistivity and functions as a current spreading layer.…”

mentioning

confidence: 99%

“…Ti is chosen for its low work function and robust adhesion to Ga 2 O 3 , while Au possesses low resistivity and functions as a current spreading layer. [3][4][5][6][7] On very heavily doped n-Ga 2 O 3 , specific contact resistivities in the range of 10 −5 -10 −6 Ω•cm 2 have been reported 1,2 but the bigger challenge is to make low resistance Ohmic contacts on lightly doped n-Ga 2 O 3 of the type encountered in transistor channels or rectifier drift regions, i.e. at the 10 17 cm −3 doping level.…”

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confidence: 99%

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Effect of Dry Etching to Improve Ohmic Contacts on Bulk, Lightly-Doped β-Ga₂O₃

Chiang,

Li,

Wan

et al. 2024

ECS J. Solid State Sci. Technol.

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Ti/Au is a typical Ohmic metal contact stack to n-type β-Ga2O3 but there have been few systematic studies of the use of pre-exposure of the surface to plasmas prior to metal deposition in order to lower the contact resistance. The effects of Cl2/Ar inductively coupled plasma exposure of Ga2O3 surfaces prior to deposition of Ti/Au (20/80 nm) contacts were examined through circular transfer length method measurements to determine both the contact resistance and specific contact resistivity. ICP source power, which controls ion density in the plasma is found to be more important than ion energy (~165-490 eV in these experiments). The plasma exposure improved specific contact resistivity by more than a factor of 2 in all cases for lightly n-type (10^17 cm^-3) Ga2O3 and a minimum value of 2x10^-4 Ω.cm^2 was obtained after heating at 550°C.

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A review of metal–semiconductor contacts for β-Ga₂O₃

Cited by 15 publications

References 137 publications

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga₂O₃/Electrolyte Heterojunction with High Stability

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga₂O₃/Electrolyte Heterojunction with High Stability

A review of Ga₂O₃ deep-ultraviolet metal–semiconductor Schottky photodiodes

Effect of Dry Etching to Improve Ohmic Contacts on Bulk, Lightly-Doped β-Ga₂O₃

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A review of metal–semiconductor contacts for β-Ga2O3

Cited by 15 publications

References 137 publications

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga2O3/Electrolyte Heterojunction with High Stability

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga2O3/Electrolyte Heterojunction with High Stability

A review of Ga2O3 deep-ultraviolet metal–semiconductor Schottky photodiodes

Effect of Dry Etching to Improve Ohmic Contacts on Bulk, Lightly-Doped β-Ga2O3

Contact Info

Product

Resources

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A review of metal–semiconductor contacts for β-Ga₂O₃

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga₂O₃/Electrolyte Heterojunction with High Stability

Flexible and Self-Powered Solar-Blind UV Photodetector Based on the Ti/α-Ga₂O₃/Electrolyte Heterojunction with High Stability

A review of Ga₂O₃ deep-ultraviolet metal–semiconductor Schottky photodiodes

Effect of Dry Etching to Improve Ohmic Contacts on Bulk, Lightly-Doped β-Ga₂O₃