Efficiency improvement of AlGaN-based deep-ultraviolet light-emitting diodes and their virus inactivation application

Saito, Y.; Wada, Satoshi; Nagata, Kouji; Makino, Hiroaki; Boyama, Shinya; Miwa, Hiroshi; Matsui, Shinichi; Kataoka, Keita; Narita, Toshio; Horibuchi, Kayo

doi:10.35848/1347-4065/ac10f2

Cited by 25 publications

(8 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The ternary alloy of III-nitrides, AlGaN, possesses large and adjustable direct band gaps ranging from 3.4 to 6.2 eV, and thus it becomes a promising material for detection and luminescence devices working in the ultraviolet (UV) wavelength. − Peculiarly, the ability of killing most germs and viruses of AlGaN-based deep-UV diodes attracts increasing attention toward this material since the pandemic of COVID-19. − The nontoxicity of AlGaN and miniaturization and stability of deep-UV diodes compared with traditional mercury lamps further promote demands and advances for AlGaN-related materials . Due to the absence of homoepitaxial substrates, heteroepitaxial substrates including sapphire, − silicon carbide, and silicon , are currently applied for AlGaN growth.…”

Section: Introductionmentioning

confidence: 99%

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Chen

Zang

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

The epitaxy of III-nitrides on metallic substrates is competitive due to the advantages of vertical carrier injection, enhanced heat dissipation, and flexible application in various IIInitride-based devices. However, the serious lattice mismatch, atom diffusion, and interface reaction under the rigorous growth conditions have caused enormous obstacles. Based on the thermal and chemical stability of the graphene layer, we propose the van der Waals epitaxy of c-oriented wurtzite AlGaN on the polycrystalline Mo substrate by high-temperature metal−organic chemical vapor deposition. The insertion of a graphene layer interrupts the chaotic epitaxial relationship between the polycrystalline metal and epilayers, resulting in the single-crystalline orientation along the wurtzite (0002) plane and residual stress release in AlGaN because of the weak van der Waals interaction. We also demonstrate that the epitaxy of AlGaN on Mo metal possesses enhanced heat dissipation ability, in which the epilayer temperature is controlled at only 28.7 °C by the heating of a ∼54 °C hot plate. The heat dissipation enhancement for the present epitaxial structures provides a desirable strategy for the fabrication of efficient ultraviolet devices with excellent stability and lifetime.

show abstract

Section: Introductionmentioning

confidence: 99%

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Chen

Zang

Zhang

et al. 2022

ACS Appl. Mater. Interfaces

View full text Add to dashboard Cite

show abstract

“…[1,2] Compared with conventional mercury discharge lamps, LEDbased DUV light sources can realize size reduction, lower energy consumption, and the reduced environmental risk. These advantages potentially meet the worldwide demand for devices that inactivate viruses [3] and sterilize water. [4] Although recent studies have reported external quantum efficiencies (EQEs) in excess of 10% for AlGaN-based LEDs with an emission wavelength of %280 nm, [5][6][7][8] further improvement is required for these devices to be used in practical applications.…”

Section: Introductionmentioning

confidence: 99%

Comprehensive Study of Electron Conduction and Its Compensation for Degenerate Si‐Doped AlN‐Rich AlGaN

Kataoka

Narita

Yagi

et al. 2023

Physica Rapid Research Ltrs

Self Cite

View full text Add to dashboard Cite

The resistivity, electron concentration, mobility, and luminescence property of AlGaN epilayers with various AlN contents (x) are systematically investigated as a function of Si‐doping concentration ([Si]). In x of 59–78%, the resistivity decreases with increasing [Si] up to 4 × 1019 cm−3. The temperature dependence of the electron concentration and mobility disappears in the optimum doping range, characteristic of electric degeneracy. The ionization energy of isolated Si donor (Ed0) is slightly increased in the range of 60–80 meV with increasing x (59–78%). At higher [Si] than 4 × 1019 cm−3, self‐compensation defects such as III vacancy–Si complexes are formed, resulting in higher resistivity. When x is 89%, the resistivity is approximately one order of magnitude higher than that for lower x, and the Ed0 is drastically increased to ≈120 meV, which is a feature of a highly compensated semiconductor. Based on the increased oxygen incorporation and the distinctive defect luminescence peak for the sample with x of 89%, the formation of acceptor‐type O‐related defects such as O‐DX and VIII‐nON is indicated and can contribute to a part of the electron compensation.

show abstract

“…These LEDs are considered replacements for the mercury lamps used in water and air sterilizations [1][2][3]. Deep-UV light with an emission wavelength below 290 nm can rapidly inactivate the deoxyribonucleic acid of virus and bacteria [4,5]; however, the light-emission efficiency (LEE) of deep-UV LEDs is considerably lower than that of low-pressure mercury lamps. The wall-plug efficiency of mass-produced deep-UV LEDs is a maximum of 10% because of the UV light absorption of the p-type gallium nitride (GaN) contact layer [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Improvement of Algan Homoepitaxial Tunnel Junction Deep-UV Light-Emitting Diodes by Controlling the Growth of N-Type Algan and Polycrystalline Mgzno/Al Electrodes

Nagata¹,

Matsubara²,

Saito³

et al. 2023

Preprint

View full text Add to dashboard Cite

Deep-ultraviolet (UV) light-emitting diodes (LEDs) based on AlGaN crystals have low light-emission efficiency; therefore, there is a need to improve this light-emission efficiency for a wide range of applications such as water and air sterilizations. UV-light-transparent device structures are considered one of the many solutions toward increasing light output power. To this end, the present study focused on developing a transparent AlGaN-based tunnel junction (TJ) as the anode of a deep-UV LED. Deep-UV LEDs composed of n+/p+-type AlGaN TJs were fabricated under the growth condition that reduced the carrier compensation in the n+-type AlGaN layers. The operating voltage was 10.8 V under the direct current (DC) operation of 63 A/cm2. In addition, magnesium zinc oxide (MgZnO)/Al reflective electrodes were fabricated to enhance the output power of the AlGaN homoepitaxial TJ LED. The output power was 57.3 mW under a DC operation of 63 A/cm2, and it was 1.7 times higher than that realized using the conventional Ti/Al electrodes. The combination of the AlGaN-based TJ and MgZnO/Al reflective contact allows further improvement of the light output power. This study confirms that the AlGaN TJ is a promising UV-transmittance structure that can obtain a high light-extraction efficiency.

show abstract

Efficiency improvement of AlGaN-based deep-ultraviolet light-emitting diodes and their virus inactivation application

Cited by 25 publications

References 59 publications

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Van der Waals Epitaxy of c-Oriented Wurtzite AlGaN on Polycrystalline Mo Substrates for Enhanced Heat Dissipation

Comprehensive Study of Electron Conduction and Its Compensation for Degenerate Si‐Doped AlN‐Rich AlGaN

Improvement of Algan Homoepitaxial Tunnel Junction Deep-UV Light-Emitting Diodes by Controlling the Growth of N-Type Algan and Polycrystalline Mgzno/Al Electrodes

Contact Info

Product

Resources

About