Growth and conductivity control of high quality AlGaN and its application to high-performance ultraviolet laser diodes

Amano, Hiroshi; Nagamatsu, Kentaro; Takeda, Kenta; Mori, Toshiaki; Tsuzuki, Hirotoshi; Iwaya, Motoaki; Kamiyama, Satoshi; Akasaki, Isamu

doi:10.1117/12.808381

Cited by 9 publications

(7 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…10) One of the reasons for this relatively low efficiency is related to the difficulty in fabricating p-type AlGaN because the activation energy of Mg increases with the Al composition ratio. 11) Therefore, a p-GaN layer is often used as the p-layer; in particular, a thick p-GaN layer (thickness of 100 nm or more) is often used as the p-type contact layer. 6,[12][13][14][15][16][17][18][19] In this case, since most of the light emitted from the active layer is absorbed in the p-layer, the EQE decreases owing to the decrease in light extraction efficiency.…”

mentioning

confidence: 99%

Improving light output power of AlGaN-based deep-ultraviolet light-emitting diodes by optimizing the optical thickness of p-layers

Matsukura

Inazu

Pernot

et al. 2021

Appl. Phys. Express

View full text Add to dashboard Cite

In this study, we investigated the relationship of light output power with the optical thickness of the p-layers in AlGaN-based deep ultraviolet light-emitting diodes with a transparent high-Al-composition p-AlGaN clad layer, a thin p-GaN contact layer, and a reflective p-type electrode. By adjusting the thickness of the transparent high-Al-composition p-AlGaN clad layer, we observed a marked change in light output power. A maximum light output power of 385 mW at 1500 mA, a maximum external quantum efficiency of 15.7% at 10 mA, and a maximum wall-plug efficiency of 15.3% at 10 mA were obtained at an emission wavelength of 275 nm.

show abstract

mentioning

confidence: 99%

Improving light output power of AlGaN-based deep-ultraviolet light-emitting diodes by optimizing the optical thickness of p-layers

Matsukura

Inazu

Pernot

et al. 2021

Appl. Phys. Express

View full text Add to dashboard Cite

show abstract

“…3,5 To avoid the formation of microcracks, AlGaN template is often used to replace conventional GaN template and, hence, reduce the tensile stress in the thick AlGaN optical CLs. 2,15 The thick AlGaN-based optical CLs and the GaN-based waveguide layers, together with the QWs and contact layers, often add up to a total thickness of 6−7 μm. However, it is quite challenging to grow crack-free high-quality AlGaN-containing 6−7 μm thick film on Si substrate.…”

mentioning

confidence: 99%

“…Furthermore, a huge misfit in coefficient of thermal expansion (CTE) between AlGaN and Si substrate usually induces a large tensile stress in the epitaxial film, and hence limits the maximum thickness of crack-free epitaxial film directly grown on Si. To reduce the threshold current of UV-LDs, AlGaN-based optical cladding layers (CLs) with a relatively high Al content (∼10%) are usually utilized to enhance the optical confinement of the active region. , To avoid the formation of microcracks, AlGaN template is often used to replace conventional GaN template and, hence, reduce the tensile stress in the thick AlGaN optical CLs. , The thick AlGaN-based optical CLs and the GaN-based waveguide layers, together with the QWs and contact layers, often add up to a total thickness of 6–7 μm. However, it is quite challenging to grow crack-free high-quality AlGaN-containing 6–7 μm thick film on Si substrate.…”

mentioning

confidence: 99%

Room-Temperature Electrically Injected AlGaN-Based near-Ultraviolet Laser Grown on Si

Feng

Wang

et al. 2018

ACS Photonics

View full text Add to dashboard Cite

This letter reports a successful fabrication of room-temperature electrically injected AlGaN-based near-ultraviolet laser diode grown on Si. An Al-composition step down-graded AlN/AlGaN multilayer buffer was carefully engineered to not only tackle the huge difference in the coefficient of thermal expansion between AlGaN template and Si substrate, but also reduce the threading dislocation density caused by the large lattice mismatch. On top of the crack-free n-AlGaN template, high quality InGaN/AlGaN quantum wells were grown, sandwiched by waveguide and optical cladding layers, for the fabrication of edge-emitting laser diode. A dramatic narrowing of the electroluminescence spectral line-width, an elongated far-field pattern, and a clear discontinuity in the slope of light output power plotted as a function of the injection current provide an unambiguous evidence of lasing.

show abstract

“…While the ionization energy of Mg acceptors in GaN is 170 meV , that in AlN is 600 meV . Therefore, p‐type AlGaN especially with high AlN mole fraction shows very low hole concentrations .…”

Section: Introductionmentioning

confidence: 98%

Polarization dilution in a Ga‐polar UV‐LED to reduce the influence of polarization charges

Yasuda

Hayashi

Katsuno

et al. 2015

Physica Status Solidi (a)

View full text Add to dashboard Cite

are laureates of the Nobel Prize in Physics 2014.We investigated the influence of polarization charges in nitride-based semiconductors. The influence due to polarization charges was calculated excluding the influences of the band offset. We found that the polarization charges (1 Â 10 13 cm À2 ) resulted in an energy spike of more than 100 meV at the location of the charges, which is a similar value to the band offset. We then proposed the concept of polarization dilution to suppress the energy spike for better hole transport by using a graded Mg-doped AlGaN layer in UV-LEDs. Device simulation results indicate lower operating voltage and higher injection efficiency by using the polarization dilution. So far, our actual 350 nm LED with the polarization dilution showed lower operating voltage. These results suggested such polarization-charge management is important in the design of the nitride semiconductors.

show abstract

Growth and conductivity control of high quality AlGaN and its application to high-performance ultraviolet laser diodes

Cited by 9 publications

References 0 publications

Improving light output power of AlGaN-based deep-ultraviolet light-emitting diodes by optimizing the optical thickness of p-layers

Improving light output power of AlGaN-based deep-ultraviolet light-emitting diodes by optimizing the optical thickness of p-layers

Room-Temperature Electrically Injected AlGaN-Based near-Ultraviolet Laser Grown on Si

Polarization dilution in a Ga‐polar UV‐LED to reduce the influence of polarization charges

Contact Info

Product

Resources

About