Dominance of radiative recombination from electron-beam-pumped deep-UV AlGaN multi-quantum-well heterostructures

Tabataba-Vakili, Farsane; Wunderer, Thomas; Kneissl, Michael; Yang, Zhihong; Teepe, Mark; Batres, Max; Feneberg, Martin; Vancil, Bernard; Johnson, N. M.

doi:10.1063/1.4967220

Cited by 36 publications

(37 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Definitely, this is quite influenced by the crystalline quality of the active region, since we did find the output power saturation with increasing e‐beam current up to 10–40 mA for the poor crystalline quality sample. One should also note that the total power efficiency is not high enough yet, about 0.3%, which is actually comparable with that obtained by Tabataba‐Vakili et al The relatively low efficiency value in comparison with the above experiments is partly due to the absence of an Al‐mirror coating on the surface of the structure. Although the power efficiency of our e‐beam‐pumped UVC light source is somewhat lower, its extraordinarily high‐output‐power at the level of Watts makes this UVC light source practically important for applications in water/air purification, sterilization, etc.…”

supporting

confidence: 80%

“…This provides a unique advantage over conventional LEDs at UVC range, since the p‐type doping for high‐Al‐content AlGaN is extremely difficult. In fact, e‐beam‐pumped UVC light sources make rapid progress in recent years and their output power increases up to 100–230 mW at ≈240 nm, which is higher than 150–180 mW reported for the best UVC LEDs emitting at a longer wavelength of 280 nm …”

mentioning

confidence: 90%

“…A promising approach that dramatically improves the light output power is electron‐beam (e‐beam) pumping, especially for the short‐wavelength UVC spectral range . This approach allows one to bypass the need for p‐type or n‐type injection layers and, thus, can largely increase the carrier injection efficiency.…”

mentioning

confidence: 99%

See 2 more Smart Citations

Deep Ultraviolet Light Source from Ultrathin GaN/AlN MQW Structures with Output Power Over 2 Watt

Wang

Rong

Иванов

et al. 2019

Advanced Optical Materials

View full text Add to dashboard Cite

which are environmentally friendly and enable portability and high efficiency. Up to date, great progress has been made on the UVC light-emitting diodes (LEDs) by using active regions of AlGaN multiple quantum wells (MQWs) .[8-14] However, the optical output power of current UVC LEDs drops significantly as the light emission wavelength gets shorter. Those LEDs suffer from poor hole injection efficiency in high-Al-content p-type AlGaN, low internal quantum efficiency (IQE) caused by large-lattice-mismatch heteroepitaxy, and strong quantum-confined Stark effect (QCSE), as well as the absorption by the nontransparent GaN contact layers. [15][16][17] A promising approach that dramatically improves the light output power is electron-beam (e-beam) pumping, especially for the short-wavelength UVC spectral range. [3,[18][19][20][21][22][23][24] This approach allows one to bypass the need for p-type or n-type injection layers and, thus, can largely increase the carrier injection efficiency. This provides a unique advantage over conventional LEDs at UVC range, since the p-type doping for high-Al-content AlGaN is High-output-power electron-beam (e-beam) pumped deep ultraviolet (DUV) light sources, operating at 230-270 nm, are achieved by adjusting the well thickness of binary ultrathin GaN/AlN multiple quantum wells. These structures are fabricated on high-quality thermally annealed AlN templates by metal-organic chemical vapor deposition. Owing to the reduced dislocation density, large electron-hole overlap, and efficient carrier injection by e-beam, the DUV light sources demonstrate high output powers of 24.8, 122.5, and 178.8 mW at central wavelengths of 232, 244, and 267 nm, respectively. Further growth optimization and employing an e-gun with increased beam current lead to a record output power of ≈2.2 W at emission wavelength of ≈260 nm, the key wavelength for water sterilization. This work manifests the practical levels of high-output-power DUV light sources operated by using e-beam pumping method. The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adom.201801763.Solid-state deep ultraviolet (DUV) optoelectronic devices in the spectral range of 200-280 nm, i.e., ultraviolet-C (UVC), have attracted much attention for their wide applications in sterilization, medical treatment, security, solar-blind photodetection, and so on. [1][2][3][4][5][6][7] Currently, Al(Ga)N material system is the most promising candidate for solid-state UVC light sources

show abstract

supporting

confidence: 80%

mentioning

confidence: 90%

See 1 more Smart Citation

Deep Ultraviolet Light Source from Ultrathin GaN/AlN MQW Structures with Output Power Over 2 Watt

Wang

Rong

Иванов

et al. 2019

Advanced Optical Materials

View full text Add to dashboard Cite

show abstract

“…[ 17 ] (≈0.75% at 267 nm), Tabataba‐Vakili et al. [ 18 ] (≈0.43% at 246 nm), and Jmerik et al. [ 19 ] (≈0.75% at 235 nm).…”

Section: Introductionmentioning

confidence: 99%

On‐Chip Mercury‐Free Deep‐UV Light‐Emitting Sources with Ultrahigh Germicidal Efficiency

Sharma

Tan

Shendre

et al. 2021

Advanced Optical Materials

View full text Add to dashboard Cite

In the current COVID‐19 scenario, there is an urgent need for developing efficient and mercury‐free deep‐ultraviolet (deep‐UV) light sources for disinfection applications. AlGaN‐based light‐emitting diodes (LEDs) may be considered as an alternative, but due to their inherent low efficiencies in the deep‐UV spectral region, significant developments are required to address efficiency issues. Here, a mercury‐free chip‐size deep‐UV light source is shown which is enabled by high‐vacuum chip‐scale cavity sealing overcoming the limitations of both mercury lamps and deep‐UV LEDs. These deep‐UV chips are cathodoluminescence based, in which a cavity is created with high vacuum integrity for efficient field‐emission. These chips demonstrate optical output power ≥20 mW (efficiency ≈4%) and, owing to the spectral overlap of phosphor cathodoluminescence spectra and germicidal effectiveness curve, resulted in log 6 (99.9999%) germicidal efficiency. Additionally, these chips offer high reliability, “instant” ON/OFF capability, high operational lifetimes, and low‐temperature dependence with complete design freedom.

show abstract

“…To address these issues, the electron beam pumped method was employed by several groups for the UVC–excitation from nitrides semiconductors. The device fabricated with this method, UVC light source tubes, has no requirement for a low-conductivity p-type layer, which is a unique advantage over the conventional UVC–LEDs [ 20 , 21 , 22 , 23 ]. However, to avoid the issues related to the conventional thermionic e-beam pumped method, such as the hot emission nature of metallic cathode and the high accelerating voltage, CNT field emission (FE) was utilized as the excitation source for electrons in UVC light sources [ 24 , 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

Optimized Aluminum Reflector for Enhancement of UVC Cathodoluminescence Based-AlGaN Materials with Carbon Nanotube Field Emitters

et al. 2021

View full text Add to dashboard Cite

The far ultraviolet C (UVC) light sources based on carbon nanotube (CNT) field emitters as excitation sources have become promising light sources for sterilization, disinfection, and water purification. However, the low light extraction efficiency of UVC–CNT light sources still hinders the practical application of these structures. Herein, we report an optimized aluminum (Al) reflector to enhance the light extraction efficiency of UVC–CNT light sources. Optical analysis of UVC-CNT light sources covered by the Al reflectors with various thicknesses ranging from 30 to 150 nm was performed to realize the optimized reflector. The UVC-CNT light sources exhibit the highest light extraction efficiency when the Al reflector layer has an optimized thickness of 100 nm. For comparison, the cathodoluminescence (CL) spectra were recorded for UVC–CNT light sources with and without the optimized Al reflector. The measured light output power and the estimated power efficiency of the UVC–CNT light-source-tube with Al reflector were enhanced by about 27 times over the reference. This enhancement is mainly attributed to the outstanding reflection effect of the Al reflector.

show abstract

Dominance of radiative recombination from electron-beam-pumped deep-UV AlGaN multi-quantum-well heterostructures

Cited by 36 publications

References 20 publications

Deep Ultraviolet Light Source from Ultrathin GaN/AlN MQW Structures with Output Power Over 2 Watt

Deep Ultraviolet Light Source from Ultrathin GaN/AlN MQW Structures with Output Power Over 2 Watt

On‐Chip Mercury‐Free Deep‐UV Light‐Emitting Sources with Ultrahigh Germicidal Efficiency

Optimized Aluminum Reflector for Enhancement of UVC Cathodoluminescence Based-AlGaN Materials with Carbon Nanotube Field Emitters

Contact Info

Product

Resources

About