InGaN/GaN nanopillar‐array light emitting diodes

Abstract

GaN light emitting diodes were fabricated from arrays of nanopillars with embedded InGaN quantum wells. InGaN heterostructures were grown by MOCVD on n-type GaN templates and pillars were fabricated by laser interference lithography and subsequent reactive ion etching and annealing. The tops of the pillars were coalesced by lateral growth of p-type GaN by MBE forming a planar contact layer. This structure enables integration with standard planar processing while taking advantage of the nanopillar structure. LEDs were fabricated and characterized by electroluminescence, current-voltage, and output power vs. current measurements. The devices showed rectifying behavior with a turn-on voltage of 3 V and electroluminescence peak at 400 nm.

Fabrication and Optical Characterization of GaN-Based Nanopillar Light Emitting Diodes

“…[2] For InGaN/GaN multiple quantum well (MQW)-based LED, the nanopillar structures may relieve strain and thus accommodate the large lattice mismatch at hetero-interface, which can enhance the radiative recombination efficiency and thus the internal quantum efficiency of the LED device. [5] Due to the large sidewall surface of nanopillars, light extract efficiency can also be improved. [2] In addition, the inclined threading dislocations may cease in the nanopillar's side surface and decrease dislocation density, which can reduce the nonradiative recombination efficiency and thus improves the device performance significantly.…”

“…As a result of the aforementioned reasons, GaNbased nano-LED exhibits a promising improvement of performance compared with the as-grown LED. [2][3][4][5]18] For GaN-based materials, the fabrication of nanostructures is usually operated in two ways, one is bottom-up and the other is top-down. The former is a direct growth approach including MOCVD, HVPE and MBE, etc.…”

The fabrication of GaN-based nanopillar light-emitting diodes

“…1 Recently, due to the great advantages of the nanostructures over the bulk material, they have acquired many useful device applications such as super-bright LEDs, full color displays, etc. 3 Due to the large sidewall surface of nanopillars, light extraction efficiency can also be improved. 3 Due to the large sidewall surface of nanopillars, light extraction efficiency can also be improved.…”

“…[2][3][4][5][6] It is known that Ni is a good mask metal and has a very high etching rate ratio for the selective etching. [2][3][4][5][6] It is known that Ni is a good mask metal and has a very high etching rate ratio for the selective etching.…”

The investigation on strain relaxation and double peaks in photoluminescence of InGaN/GaN MQW layers

“…The strain effect can also degrade the luminescence properties of InGaN/GaN MQW [11][12][13]. It is known that fabrication of nanostructures can relieve strain and improve luminescence properties of the InGaN/GaN MQW due to the large surface-to-volume ratio [2,14]. In fact, the strain relaxation can be clearly observed in nanopillar samples according to the blue shift in the PL peak position.…”