Improvement of brightness with Al2O3 passivation layers on the surface of InGaN/GaN-based light-emitting diode chips

Unleashing the potential of molecular beam epitaxy grown AlGaN-based ultraviolet-spectrum nanowires devices

“…132,133 Among other uses, SiO x has also been used to selectively block the threading dislocation in epitaxially grown LED structures to increase the quantum efficiency 134 and contribute to increasing the output power of LED with an optimized refractive index gradient. 135 Al 2 O 3 is another passivation material for improving the blue LED brightness 136 and reducing the leakage current. 137 Double layer Al 2 O 3 ∕SiO x demonstrated the higher power output by simultaneously passivating the GaN surface and increasing the critical angle of the light escape cone.…”

Two-step passivation for enhanced InGaN/GaN light emitting diodes with step graded electron injectors

“…A common passivation approach is a thin layer of dielectric coating covering the entire LED die surface followed by opening windows for contact pads after metalization [12e15,17e20]. Deposition of the aforementioned dielectric layer generally can be done by plasmaenhanced chemical vapor deposition (PECVD) [13,14,17e19], sputtering [12] or atomic layer deposition (ALD) [13]. Passivation is particularly important for elimination of shortening during the packaging step which is characteristic to lateral configuration of InGaN/GaN LED dies on sapphire.…”

“…The plasma damage manifests itself as generation of point defects, primarily nitrogen vacancies, which act as donors [27,28]. There are other ways to improve light output such as using encapsulants with high refractive indices [29,30], patterning of current spreading layer surface [21,31], using patterned sapphire substrates [13], patterning of passivation layer surface [13,14], and employing antireflection optical coatings and two-dimensional photonic crystals [12,32]. One of the practical ways for light extraction improvement of front emitting LED chip that does not degrade its electrical properties is patterning of the passivation layer [13,14].…”

Enhanced Performance of GaN-Based Light-Emitting Diodes on Patterned Sapphire Substrate with a Novel Patterned SiO2/Al2O3 Passivation Layer

“…Therefore, improved light extraction efficiency of GaN-based LEDs is essential for futuristic applications. In recent years, a surface passivation layer had been introduced to improve the optical and electrical performances of the LEDs both theoretically and experimentally, such as a traditional SiO 2 passivation layer [2] , a SiN x passivation layer [3] , a SiON x passivation layer [4] , a sulfide passivation layer [5] , and an Al 2 O 3 passivation layer [6] , etc. In this work, GaN-based LEDs on patterned sapphire substrate (PSS) with a novel patterned SiO 2 /Al 2 O 3 passivation layer have been proposed and fabricated for the first time.…”