Milliwatt power 270 nm‐band AlGaN deep‐UV LEDs fabricated on ELO‐AlN templates

Abstract

We demonstrated CW milliwatt power operations of 270 nm‐band AlGaN multi‐quantum well (MQW) deep‐ultraviolet (DUV) light‐emitting diodes (LEDs) fabricated on epitaxial lateral overgrowth (ELO) AlN templates on sapphire. An initial AlN stripe layer was grown directly on sapphire by using ammonia (NH3) pulse‐flow multilayer (ML) growth method. An AlN stripe structure with a width of 5 μm and a spacing of 3 μm was completely coalesced after the growth of an approximately 15 μm‐thick ELO‐AlN layer grown by low‐pressure metal‐organic chemical vapor deposition (LP‐MOCVD). The edge‐type threading dislocation density (TDD) of the wing region of the ELO‐AlN layer was 3×108 cm‐2, as observed by cross‐sectional transmission electron microscope (TEM) image. The maximum output power of 2.7 mW was obtained from an AlGaN MQW LED with emission wavelength at 273 nm fabricated on ELO‐AlN template under room temperature (RT) CW operation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

High-quality AlN epitaxy on nano-patterned sapphire substrates prepared by nano-imprint lithography

“…1(b). It is found that the AlN epilayer has completely coalesced in a thickness about 3 μm, which is less than the previously reported coalescence thickness for AlN grown on micro-stripe patterned substrates via ELO technique412. It should be ascribed to the nano-scale patterns on the substrate and the effective control of the AlN lateral growth.…”

AlGaN-based deep-ultraviolet light-emitting diodes grown on High-quality AlN template using MOVPE

“…As compact solid-state devices, DUV LEDs have many advantages over the traditional mercury lamp, and are deemed as the future UV light source. Nevertheless, compared with the great success of InGaN-based blue LEDs, the present performance of AlGaN-based DUV LEDs is still far from satisfactory though some progress has been made [3][4][5][6][7]. AlGaNbased DUV LEDs have been mostly grown on sapphire substrates.…”

Status of Growth of Group III-Nitride Heterostructures for Deep Ultraviolet Light-Emitting Diodes

“…[72,[77][78][79] Significant reduction in TDD was observed in the areas between ridges. A maximum output power of 2.7 mW under CW operation of 273 nm DUV LEDs on ELO AlN templates with the wing region having TDD of 3×10 8 cm -2 has been reported by Hirayama et al [80] By reducing the TDD in AlN layers on sapphire from 10 10 cm −2 to 10 9 cm −2 , output powers of 1mW and about 4mW for 295 nm and 324 nm LEDs, respectively, have been demonstrated by Kueller et al [69] This method has also been applied for growing AlN template on Si (111) substrate, as illustrated in Figure 7. ELO AlN templates on Si (111) substrate with FWHM values of 920 and 780 arcsec for XRD ω-rocking curves from the (0002) and (101 1) reflections, respectively, with simultaneous reduction in crack density have been achieved by Zhang et al [81] A peak pulsed power and slope efficiency of ~0.6 mW and ~1.3 mW/mA, respectively, were demonstrated for 359 nm UV LEDs after removing the Si (111) substrate.…”