纳米压印制备的光子晶体结构对AlGaN基材料深紫外出光效率的提高
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摘要
通过利用阳极氧化铝的方法制备高度有序的光子晶体结构作为纳米压印模板,将大面积光子晶体图案转移到了样品表面,解决了国际上小尺寸光子晶体制备困难的问题。采用纳米压印的方法在AlGaN基样品表面上制备了290 nm的周期光子晶体结构,并将表面具有光子晶体结构的AlGaN基样品正面出光强度提高121%。偏振特性的实验结果表明六角排列的孔状光子晶体将原来朝向样品侧面传播的TE偏振光偏折转向正面,从而增加光抽取效率,改变出光偏振度。指出远场角分辨图案的变化归因于光子晶体对出光的衍射和Bragg散射效果。实验中采用的创新性工艺可以用来制备具有高出光效率的深紫外发光二极管。
Photonic crystal structures of 290 nm period were fabricated on the surface of AlGaN layer by nanoimprint lithography.Highly ordered porous anodic aluminum oxide was adopted as a convenient approach for large area of PhC pattern transferred.In contrast to a planar sample,both intensity and radiation profile of surface emission from AlGaN materials with PhCs structures were improved significantly.Honeycomb PhC structures deflected the original in-plane vector of TE guided light.The modified radiation profile was attributed to the diffraction and Bragg scattering effects of PhCs.The results would be helpful to enhancing surfacing emission and ameliorate polarization properties of deep-UV LEDs.
Photonic crystal structures of 290 nm period were fabricated on the surface of AlGaN layer by nanoimprint lithography.Highly ordered porous anodic aluminum oxide was adopted as a convenient approach for large area of PhC pattern transferred.In contrast to a planar sample,both intensity and radiation profile of surface emission from AlGaN materials with PhCs structures were improved significantly.Honeycomb PhC structures deflected the original in-plane vector of TE guided light.The modified radiation profile was attributed to the diffraction and Bragg scattering effects of PhCs.The results would be helpful to enhancing surfacing emission and ameliorate polarization properties of deep-UV LEDs.
引文
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[3]Hirayama H,Fujikawa S,Noguchi N,et al.222-282 nm AlGaN and InAlGaN-based deep-UV LEDs fabricated on highquality AlN on sapphire[J].Phys.Stat.Sol.A,2009,206(6):1176-1182.
[4]David A,Benisty H,Weisbuch C.Photonic crystal light-emitting sources[J].Rep.Prog.Phys.,2012,75(12):126501-1-38
[5]Durnev M V,Karpov S Y.Polarization phenomena in light emission from c-plane Al(In)GaN heterostructures[J].Phys.Stat.Sol.B,2013,250(1):180-186.
[6]Fujii T,Gao Y,Sharma R,et al.Increase in the extraction efficiency of GaN-based light-emitting diodes via surface roughening[J].Appl.Phys.Lett.,2004,84(6):855-857.
[7]Huh C,Lee K S,Kang E J,et al.Improved light-output and electrical performance of InGaN-based light-emitting diode by microroughening of the p-GaN surface[J].J.Appl.Phys.,2003,93(11):9383-9385.
[8]Xi Q J,Schubert M F,Kim J K,et al.Optical thin-film materials with low refractive index for broadband elimination of Fresnel reflection[J].Nat.Photon.,2007,1(3):176-179.
[9]Kim J B,Kim S M,Kim Y W,et al.Light extraction enhancement of GaN-based light-emitting diodes using volcanoshaped patterned sapphire substrates[J].J.Appl.Phys.,2010,49(4):042102-1-3.
[10]David A,Benisty H,Weisbuch C.Optimization of light-diffracting photonic-crystals for high extraction efficiency LEDs[J].J.Disp.Technol.,2007,3(2):133-148.
[11]Matioli E,Rangel E,Iza M,et al.High extraction efficiency light-emitting diodes based on embedded air-gap photoniccrystals[J].Appl.Phys.Lett.,2010,96(3):031108-1-3.
[12]Byeon K J,Hong E J,Park H,et al.Full wafer scale nanoimprint lithography for GaN-based light-emitting diodes[J].Thin Solid Film,2011,519(7):2241-2246.
[13]Yanagishita T,Nishio K,Masuda H.Two-dimensional photonic crystal composed of ordered polymer nanopillar arrays with high aspect ratios using anodic porous alumina templates[J].Appl.Phys.Exp.,2008,1(1):012002-1-4.
[14]Zhou W,Min G,Song Z,et al.Enhanced efficiency of light emitting diodes with a nano-patterned gallium nitride surface realized by soft UV nanoimprint lithography[J].Nanotechnol.,2010,21(20):205304-1-5.
[15]Zhou W,Zhang J,Li X,et al.Replication of mold for UV-nanoimprint lithography using AAO membrane[J].Appl.Surf.Sci.,2009,255(18):8019-8022.
[16]McGroddy K,David A,Matioli E,et al.Directional emission control and increased light extraction in GaN photonic crystal light emitting diodes[J].Appl.Phys.Lett.,2008,93(10):103502-1-3.
[17]Fu X X,Zhang B,Kang X N,et al.GaN-based light-emitting diodes with photonic crystals structures fabricated by porous anodic alumina template[J].Opt.Express,2011,19(105):A1104-A1108.
[18]Nam K B,Li J,Nakarmi M L,et al.Unique optical properties of AlGaN alloys and related ultraviolet emitters[J].Appl.Phys.Lett.,2004,84(25):5264-5266.
[19]Sigmund O,Hougaard K.Geometric properties of optimal photonic crystals[J].Phys.Rev.Lett.,2008,100(15):153904-1-4.
[20]Matioli E,Brinkley S,Kelchner K M,et al.High-brightness polarized light-emitting diodes[J].Light:Sci.Appl.,2012,1(8):e22-1-7.