AlN/AlGaInN superlattice light-emitting diodes at 280 nm

Kipshidze, G.; Kuryatkov, V.; Zhu, Kaigui; Borisov, B.; Holtz, M.; Nikishin, S. A.; Temkin, H.

doi:10.1063/1.1535255

Cited by 78 publications

(69 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…We have shown that DAS containing as many as 400 well-barrier pairs can be reproducibly grown by GSMBE with excellent structural and optical properties. 1,4,6) When doped with Mg, room temperature hole concentrations of 1 Â 10 18 cm À3 were obtained in DAS with an average AlN content of $65%. 4,6,16) In similar DAS doped with Si, electron concentrations of 3 Â 10 19 cm À3 , were reached with room temperature mobility of 10 -20 cm 2 /(VÁs).…”

Section: Introductionmentioning

confidence: 99%

“…1,4,6) When doped with Mg, room temperature hole concentrations of 1 Â 10 18 cm À3 were obtained in DAS with an average AlN content of $65%. 4,6,16) In similar DAS doped with Si, electron concentrations of 3 Â 10 19 cm À3 , were reached with room temperature mobility of 10 -20 cm 2 /(VÁs). 4,6) Based on n-and p-type DAS of AlN/Al 0:08 Ga 0:92 N, we have prepared UV LEDs with peak emission at 280 -290 nm and 262 nm.…”

Section: Introductionmentioning

confidence: 99%

“…The energy gap smoothly increases from 3.4 in GaN to 6.2 eV in AlN, providing a wide range of possible emission wavelengths. However, device preparation is fundamentally limited by the difficulty of preparing p-type layers of large bandgap Al x Ga 1Àx N. We describe here how this limitation can be overcome, and to what extent, by the use of digital alloy structures (DAS) formed by short period superlattices (SLs) consisting of 3 -6 monolayer (ML) thick barriers of AlN and 2 -3 ML thick wells of Al x Ga 1Àx N. 1,4,6,12) The average DAS composition and therefore the effective energy gaps of AlN/AlGaN 13) and AlN/GaN 14,15) SLs are known to depend on the well/ barrier thickness ratio, the well composition, and the SL period. We have shown that DAS containing as many as 400 well-barrier pairs can be reproducibly grown by GSMBE with excellent structural and optical properties.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Digital Alloys of AlN/AlGaN for Deep UV Light Emitting Diodes

Nikishin

Holtz

Temkin

2005

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

We report a systematic study of the optical and electrical properties of deep ultraviolet light emitting diodes based on digital alloy structures of AlN/Al0.08Ga0.92N grown by gas source molecular beam epitaxy with ammonia. Digital alloys are formed by short period superlattices consisting of Al0.08Ga0.92N wells, 0.50 or 0.75 nm thick, and AlN barriers, 0.75 to 1.5 nm thick. For digital alloys with effective bandgap of 5.1 eV, average AlN composition 72%, we obtain room temperature electron concentrations up to 1×1019 cm-3 and resistivity of 0.005 Ω·cm and hole concentrations of 1×1018 cm-3 with resistivity of 6 Ω·cm. Light emitting diodes based on digital alloys are demonstrated operating in the range of 250 to 290 nm.

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Digital Alloys of AlN/AlGaN for Deep UV Light Emitting Diodes

Nikishin

Holtz

Temkin

2005

Jpn. J. Appl. Phys.

View full text Add to dashboard Cite

show abstract

“…6 eV and the associated outstanding chemical and thermal stability, the realization of high-quality AlN epitaxial layers can widely extend the application field of III-V nitride materials versus high-temperature high-power applications, e.g. high-power field effect transistors, and opto-electronic devices, particularly, UV diodes [1][2][3]. Furthermore, AlN/ GaN superlattice structures can be used in optical devices operating at telecommunication wavelengths by exploiting intersubband transitions between bound quantum well states [4,5].…”

Section: Introductionmentioning

confidence: 99%

Structural and spectroscopic properties of AlN layers grown by MOVPE

Thapa

Kirchner

Scholz

et al. 2007

Journal of Crystal Growth

View full text Add to dashboard Cite

The effects on surface morphology, crystal quality, and growth rate of undoped AlN layers grown on c-plane sapphire substrates due to the changes in growth parameters, such as V-III ratio, N 2 2H 2 ratio, and growth temperature in LP-MOVPE are studied here. The optimized growth process resulted in an almost flat surface morphology with a significantly reduced number of hexagonal pits ð3 Â 10 7 cm À2 Þ and good crystalline quality having a rms value of roughness of 0.4 nm measured by atomic force microscopy and a high resolution X-ray diffraction (HRXRD) FWHM value for (0 0 0 2) reflection of 200 arcsecs. The threading dislocation density of the AlN layer is estimated approx. 10 9 cm À2 from cross-sectional transmission electron microscopy (TEM) measurements. Additionally, these optimized samples show a strong donor-bound exciton luminescence signal with a FWHM of 20 meV. Furthermore, small period AlN/ GaN superlattice structures with excellent uniformity were grown, as proven by our HRXRD and TEM studies.

show abstract

“…Thus, various methods have been developed, including p-GaN contact layer [117][118][119][120] and superlattice structures, 38,[121][122][123][124][125][126][127][128][129][130] in order to achieve efficient current injection into Al-rich p-Al x Ga 1-x N.…”

Section: 99mentioning

confidence: 99%

Review—Group III-Nitride-Based Ultraviolet Light-Emitting Diodes: Ways of Increasing External Quantum Efficiency

Park

Kim

Cho

et al. 2017

ECS J. Solid State Sci. Technol.

View full text Add to dashboard Cite

There is a rapidly growing demand for highly efficient ultraviolet (UV) light sources for a wide variety of applications. In particular, state-of-the-art AlGaN deep UV light-emitting diodes (DUV LEDs) exhibit inadequately low external quantum efficiencies (EQEs). The low efficiencies are attributed to the inherent material properties of high-Al-content AlGaN including strained epitaxial layers, low carrier concentrations, and strong transverse magnetic (TM)-polarized light emission. Extensive efforts have been made to tackle these challenging issues and technological developments have been achieved and enabled the fabrication of reasonable EQE LEDs. In this review, recent advances in the growth of high-quality AlGaN epitaxial layers, transparent and reflective ohmic contacts, and light extraction for AlGaN-based UV LEDs are reviewed. Al x Ga 1-x N-based ultraviolet light-emitting diodes (UV LEDs) are of technological importance because of their applications in numerous areas such as water purification, biological analysis, sensing, epoxy curing, high-density optical storage, white light illumination, UV adhesives, 3-dimensional (3D) printer and UV-coating.1,2 These applications are made possible because of their wide bandgap energy range in the UV spectrum, which spans from 6.2 eV (AlN) to 3.4 eV (GaN), namely, from UV-A (320-400 nm), UV-B (290-320 nm) to UV-C (200-290 nm).3-7 The external quantum efficiency (EQE) of Al x Ga 1-x N-based UV LEDs decreases rapidly as the molar fraction (x) of Al increases, namely, as the wavelength decreases, as illustrated in Figure 1. 8 Thus, a great deal of effort has been made in order to improve the EQE of UV LEDs. The effort notwithstanding, however, the EQE of AlGaN-based UV LEDs is still insufficiently low. The typical EQE of UV LEDs, specifically in the UV-C spectral range (100-280 nm), is less than 5% and decreases down to 10 -6 % for 210-nm AlN-based UV LEDs. 4 These low EQEs are associated with the intrinsic material properties of Al x Ga 1-x N.1,2 Figure 2 exhibits a schematic diagram of a typical AlGaN UV LED structure grown on a sapphire substrate. The structure consists of a Si-doped n-type AlGaN, an Al x Ga 1-x N/Al y Ga 1-y N multiple-quantum well (MQW) active region, an AlGaN-based electron-blocking layer (EBL), a Mg-doped p-type AlGaN, and a Mg-doped p-type GaN. Almost every layer in the structure poses different technical issues, which limit the efficiency of UV LEDs, as shown in Figure 2. First, increasing the Al content generally results in a poor crystallinity of AlGaN epilayers, causing a poor internal quantum efficiency (IQE). Second, both n-type and ptype doping efficiencies of AlGaN are difficult to increase because the ionization energies of acceptor (Mg) and donor (Si) dopants largely increase with increasing Al content. The low doping efficiency causes several technological problems: (i) a poor electrical efficiency (EE) attributable to high-resistance contacts on resistive n-type and p-type AlGaN; (ii) current crowding causing non-uniform current in...

show abstract

AlN/AlGaInN superlattice light-emitting diodes at 280 nm

Cited by 78 publications

References 21 publications

Digital Alloys of AlN/AlGaN for Deep UV Light Emitting Diodes

Digital Alloys of AlN/AlGaN for Deep UV Light Emitting Diodes

Structural and spectroscopic properties of AlN layers grown by MOVPE

Review—Group III-Nitride-Based Ultraviolet Light-Emitting Diodes: Ways of Increasing External Quantum Efficiency

Contact Info

Product

Resources

About