Electroluminescence of ordered ZnO nanorod array/p-GaN light-emitting diodes with graphene current spreading layer

Abstract

Ordered ZnO nanorod array/p-GaN heterojunction light-emitting diodes (LEDs) have been fabricated by introducing graphene as the current spreading layer, which exhibit improved electroluminescence performance by comparison to the LED using a conventional structure (indium-tin-oxide as the current spreading layer). In addition, by adjusting the diameter of ZnO nanorod array in use, the light emission of the ZnO nanorod array/p-GaN heterojunction LEDs was enhanced further. This work has great potential applications in solid-state lighting, high performance optoelectronic devices, and so on.PACS78.60.Fi; 85.60.Jb; 78.67.Lt; 81.10.Dn

Modulating the size of ZnO nanorods on SiO2 substrates by incorporating reduced graphene oxide into the seed layer solution

“…However, there are diversified ways to include graphene into the nanocomposite fabrication process. Based on previous reports, 7 graphene related materials were spread on top of the ZnO nanostructures 8 and a graphene layer has been inserted between the ZnO nanorod. 9 In 2015 and 2016, Pruna et al have add graphene related materials into ZnO seed layer to grow ZnO nanorod array with outstanding characteristics.…”

Direct formation of transfer-free graphene as current spreading layers on n-ZnO nanorods/p-GaN light-emitting diodes

“…[1][2][3][4]10,16,17) Since the NR structure does not constitute a continuous layer, it is necessary to deposit an additional current spreading layer for uniform current injection. 18) Recently, graphene has emerged as a promising alternative to the traditional current spreading layer of indium tin oxide used as the transparent conducting electrode because of its high transparency and good electrical conductivity. 19) Several studies have been reported on using transferred graphene prepared by chemical vapor deposition (CVD) as a current spreading layer with high transmittance.…”

“…19) Several studies have been reported on using transferred graphene prepared by chemical vapor deposition (CVD) as a current spreading layer with high transmittance. 18,20,21) However, in the previous works, the as-fabricated graphene initially grown on the surface of a metal substrate suffered from complicated transferring processes for uniformly and conformally covering all the surfaces of the nanostructures for subsequent applications. 18,20) A series of transferring processes generally involves the use of chemical solvents or reactions, whereby organic contaminants and unexpected cracks are inevitably introduced, hindering the progress of introducing graphene for the current spreading layer in nextgeneration optoelectronic devices with various nanostructured geometries.…”

“…18,20,21) However, in the previous works, the as-fabricated graphene initially grown on the surface of a metal substrate suffered from complicated transferring processes for uniformly and conformally covering all the surfaces of the nanostructures for subsequent applications. 18,20) A series of transferring processes generally involves the use of chemical solvents or reactions, whereby organic contaminants and unexpected cracks are inevitably introduced, hindering the progress of introducing graphene for the current spreading layer in nextgeneration optoelectronic devices with various nanostructured geometries. 22) In addition, it is extremely difficult to precisely transfer a specific area of a continuous graphene layer into a defined region of the fabricated nanorod arrays.…”

Single-pot ZnO nanostructure synthesis by chemical bath deposition and their applications

“…ZnO is one of the most favorable materials widely used in electronics (transistors) [4,5], sensors [6][7][8], catalysts [9][10][11], light emitting devices [12][13][14][15], piezoelectric devices [16][17][18][19][20], solar cells [21][22][23], sunscreens [24,25], lasers diodes [26,27], hydrophobic surfaces [28,29], magnetic data storage [30,31], water disinfection [32], antiviral agent [33,34], anti-cancer agent [35], hazardous waste remediation [36], flexible plastic devices [37], degradation of pollutants [38], energy conversion and storage devices [22,[39][40][41]. ZnO is a wide band gap semiconductor (3.3 eV) with a high excitation binding energy of 60meV [42] at room temperature.…”