Study of AlN based materials grown on nano-patterned sapphire substrates for deep ultraviolet LED applications

Chen, Zhaoying; Hoo, Jason; Chen, Yao; Wang, Vincent; Guo, Shiping

doi:10.7567/1347-4065/ab09de

Cited by 12 publications

(8 citation statements)

References 33 publications

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“…Since growth and doping required both accuracy and fine control of fluxes, epitaxy is used as the main deposition technique for LED fabrication. In this way, there are three epitaxial techniques more used such as molecular beam epitaxy (MBE), migration enhanced epitaxy (MEE), and metalorganic chemical vapor deposition (MOCVD) [141][142][143][144]. Besides, the development of combined methods based on MBE, MEE, and MOCVD, such as metal-source flow-rate modulation epitaxy, are of interest as long as Nitrogen flux remains constant reducing the activation energy of accep-tors and smooth surfaces could be produced [145].…”

Section: P-type Doping and Ohmic Contactsmentioning

confidence: 99%

Physical and technological analysis of the AlGaN-based UVC-LED: an extended discussion focused on cubic phase as an alternative for surface disinfection.

et al. 2022

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Crisis in coronavirus times requires understanding the effects on society and establishing efficient mechanisms to prevent infections. The disinfection of personal protection equipment by UVC light remains a key opportunity area. Therefore, this letter presents the main drawbacks and challenges on the fabrication of deep ultraviolet LEDs based on III-nitrides, such as the substrate selection, dislocation reduction, the increase of external quantum efficiency, enhancement of the radiative recombination in the active region, the complications to reach high Al content in AlGaN-based UVC LED avoiding the reduction of the p-doping, replacing the p-GaN contact layer by p-AlGaN without hindering the deposition of ohmic contacts. Furthermore, the cubic phase is suggested as a promising candidate for AlGaN UVC-LEDs applications as is discussed in this work.

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Section: P-type Doping and Ohmic Contactsmentioning

confidence: 99%

Physical and technological analysis of the AlGaN-based UVC-LED: an extended discussion focused on cubic phase as an alternative for surface disinfection.

et al. 2022

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“…Thus, the AlN epilayer is nearly stress-free. [17,36,40,42,43,46,53,56,[58][59][60]62,69,73,74,76,79,81,94,[98][99][100][101][102][103][104][105][106][107][108][109] It is noted that there has been no unified standard for the evaluation of TDD. X-ray rocking curve (XRC) scan is the most common method to evaluate TDD.…”

Section: Quasi-van Der Waals Epitaxy (Qvdwe)mentioning

confidence: 99%

“…Figure 23. Selected AlN/sapphire TDD by year of publication[17,36,40,42,43,46,53,56,[58][59][60]62,69,73,74,76,79,81,94,[98][99][100][101][102][103][104][105][106][107][108][109]. The ultralow TDD value of 3.4 × 10 7 cm −2 has been achieved by ELOG growth technique in 2006.…”

mentioning

confidence: 99%

Recent Advances in Fabricating Wurtzite AlN Film on (0001)-Plane Sapphire Substrate

Zhang

et al. 2021

Crystals

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Ultrawide bandgap (UWBG) semiconductor materials, with bandgaps far wider than the 3.4 eV of GaN, have attracted great attention recently. As a typical representative, wurtzite aluminum nitride (AlN) material has many advantages including high electron mobility, high breakdown voltage, high piezoelectric coefficient, high thermal conductivity, high hardness, high corrosion resistance, high chemical and thermal stability, high bulk acoustic wave velocity, prominent second-order optical nonlinearity, as well as excellent UV transparency. Therefore, it has wide application prospects in next-generation power electronic devices, energy-harvesting devices, acoustic devices, optical frequency comb, light-emitting diodes, photodetectors, and laser diodes. Due to the lack of low-cost, large-size, and high-ultraviolet-transparency native AlN substrate, however, heteroepitaxial AlN film grown on sapphire substrate is usually adopted to fabricate various devices. To realize high-performance AlN-based devices, we must first know how to obtain high-crystalline-quality and controllable AlN/sapphire templates. This review systematically summarizes the recent advances in fabricating wurtzite AlN film on (0001)-plane sapphire substrate. First, we discuss the control principles of AlN polarity, which greatly affects the surface morphology and crystalline quality of AlN, as well as the electronic and optoelectronic properties of AlN-based devices. Then, we introduce how to control threading dislocations and strain. The physical thoughts of some inspirational growth techniques are discussed in detail, and the threading dislocation density (TDD) values of AlN/sapphire grown by various growth techniques are compiled. We also introduce how to achieve high thermal conductivities in AlN films, which are comparable with those in bulk AlN. Finally, we summarize the future challenge of AlN films acting as templates and semiconductors. Due to the fast development of growth techniques and equipment, as well as the superior material properties, AlN will have wider industrial applications in the future.

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“…They have been widely used in various applications, such as traffic signals, full color displays, and back lights in liquid crystal displays. [1][2][3] Although GaN-based LEDs with high brightness are commercially available, the light output power of these LEDs is still limited by low internal quantum efficiency and light extraction efficiency. [4][5][6][7] Generally, a conventional GaN-based LED is grown on sapphire substrates in spite of the fact that the two have a lattice and coefficient of thermal expansion mismatch of 16% and 34%, respectively.…”

Section: Introductionmentioning

confidence: 99%

Novel patterned sapphire substrates for enhancing the efficiency of GaN-based light-emitting diodes

Chao

Yeh

et al. 2020

RSC Adv.

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Study of AlN based materials grown on nano-patterned sapphire substrates for deep ultraviolet LED applications

Cited by 12 publications

References 33 publications

Physical and technological analysis of the AlGaN-based UVC-LED: an extended discussion focused on cubic phase as an alternative for surface disinfection.

Physical and technological analysis of the AlGaN-based UVC-LED: an extended discussion focused on cubic phase as an alternative for surface disinfection.

Recent Advances in Fabricating Wurtzite AlN Film on (0001)-Plane Sapphire Substrate

Novel patterned sapphire substrates for enhancing the efficiency of GaN-based light-emitting diodes

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