Fully Flexible GaN Light‐Emitting Diodes through Nanovoid‐Mediated Transfer

Recently, achieving flexible and highly efficient light-emitting elements is the most noticeable demand for lighting or displays. Here, fully flexible gallium nitride (GaN) light-emitting diodes (LEDs) are demonstrated based on a unique transfer method. The LED structure consisting of GaN pyramid arrays are first fabricated on an amorphous glass-based template with a low-temperature gallium nitride/titanium (LT-GaN/Ti) hetero-interface, then released and embedded into a flexible or stretchable substrate using a specialized interface control. Nanovoids created during thermal annealing render the hetero-interface weaker than the other interfaces. This interface is further weakened by a post-mechanical treatment for gentle release of the GaN pyramid arrays from the interface during a transfer process. The LEDs typically have a total thickness of }70 lm and exhibit stable surface-emitting electroluminescence even at a bending radius of }2 mm with exceptionally high luminance values of 595 and 175 cd/m2 at peak wavelengths of 514 and 483 nm, respectively. The results suggest a route to high brightness, large, flexible/stretchable blue or green lighting or displays.

[1]  Eun Kyung Lee,et al.  Full-colour quantum dot displays fabricated by transfer printing , 2011 .

[2]  Jong Kyu Kim,et al.  Solid-State Light Sources Getting Smart , 2005, Science.

[3]  Y. Igasaki,et al.  Structure and Electrical Properties of Titanium Nitride Films , 1978 .

[4]  Jing Zhang,et al.  First-Principle Electronic Properties of Dilute-As GaNAs Alloy for Visible Light Emitters , 2013, Journal of Display Technology.

[5]  Y. Takano,et al.  Influence of Thermal Annealing on GaN Buffer Layers and the Property of Subsequent GaN Layers Grown by Metalorganic Chemical Vapor Deposition , 1999 .

[6]  Yun Sung Lee,et al.  GaN light-emitting diodes on glass substrates with enhanced electroluminescence , 2012 .

[7]  E. Fred Schubert,et al.  Light Emitting Diodes , 1987 .

[8]  Hongping Zhao,et al.  Analysis of Internal Quantum Efficiency and Current Injection Efficiency in III-Nitride Light-Emitting Diodes , 2013, Journal of Display Technology.

[9]  K. Delaney,et al.  Auger recombination rates in nitrides from first principles , 2009, 0904.3559.

[10]  A. Krasnov,et al.  High-contrast organic light-emitting diodes on flexible substrates , 2002 .

[11]  S. Denbaars,et al.  Semipolar $({\hbox{20}}\bar{{\hbox{2}}}\bar{{\hbox{1}}})$ InGaN/GaN Light-Emitting Diodes for High-Efficiency Solid-State Lighting , 2013, Journal of Display Technology.

[12]  Yun Sung Lee,et al.  Local Crystallization of ${\rm LaB}_{6}$ Yielding Compact, Strong Thermionic Electron Emission Source , 2013, IEEE Electron Device Letters.

[13]  Jong-Hyun Ahn,et al.  Extremely efficient flexible organic light-emitting diodes with modified graphene anode , 2012, Nature Photonics.

[14]  K. Ellmer.  Past achievements and future challenges in the development of optically transparent electrodes , 2012, Nature Photonics.

[15]  Jürgen Christen,et al.  Improving GaN-on-silicon properties for GaN device epitaxy , 2011 .

[16]  Zhenghong Lu,et al.  Oxidized Gold Thin Films: An Effective Material for High‐Performance Flexible Organic Optoelectronics , 2009, Advanced materials.

[17]  Yun Sung Lee,et al.  Nearly Perfect Polycrystalline, Large-Grained Silicon Arrays Formed at Low-Temperature Ambient by Local Pyrolysis , 2012 .

[18]  Soon-Bok Lee,et al.  Tensile and fatigue behaviors of printed Ag thin films on flexible substrates , 2012 .

[19]  M. Umeno,et al.  Thermal stability of GaN on (111)Si substrate , 1998 .

[20]  G. Yi,et al.  High-quality GaN films grown on chemical vapor-deposited graphene films , 2012 .

[21]  K. Kumakura,et al.  Layered boron nitride as a release layer for mechanical transfer of GaN-based devices , 2012, Nature.

[22]  Yonggang Huang,et al.  Printed Assemblies of Inorganic Light-Emitting Diodes for Deformable and Semitransparent Displays , 2009, Science.

[23]  John W. Hutchinson,et al.  Buckling delamination in compressed multilayers on curved substrates with accompanying ridge cracks , 2006 .

[24]  Young‐Chang Joo,et al.  Improvement of Electrical and Mechanical Properties of Ag Nanoparticulate Films by Controlling the Oxygen Pressure , 2010 .

[25]  Takashi Mukai,et al.  Superbright Green InGaN Single-Quantum-Well-Structure Light-Emitting Diodes , 1995 .

[26]  K. Miura,et al.  Infrared Femtosecond Laser Induced Visible Long-Lasting Phosphorescence in Mn2+-Doped Sodium Borate Glasses , 1999 .

[27]  John A. Rogers,et al.  Inorganic semiconductor nanomaterials for flexible and stretchable bio-integrated electronics , 2012 .

[28]  G. Yi,et al.  Transferable GaN Layers Grown on ZnO-Coated Graphene Layers for Optoelectronic Devices , 2010, Science.

[29]  S. Mohney,et al.  Estimated phase equilibria in the transition metal-Ga-N systems: Consequences for electrical contacts to GaN , 1996 .

[30]  Takashi Mukai,et al.  Improvement of Luminous Efficiency in White Light Emitting Diodes by Reducing a Forward-bias Voltage , 2007 .

[31]  A. Geim,et al.  Two-dimensional gas of massless Dirac fermions in graphene , 2005, Nature.

[32]  Un Jeong Kim,et al.  Nearly single-crystalline GaN light-emitting diodes on amorphous glass substrates , 2011 .

[33]  Takao Someya,et al.  Ultrathin, highly flexible and stretchable PLEDs , 2013, Nature Photonics.

[34]  Young Joon Hong,et al.  Selective formation of GaN-based nanorod heterostructures on soda-lime glass substrates by a local heating method. , 2011, Nanotechnology.

[35]  Peter Andersson,et al.  The Origin of the High Conductivity of Poly(3,4-ethylenedioxythiophene)−Poly(styrenesulfonate) (PEDOT−PSS) Plastic Electrodes , 2006 .

[36]  S. Nakamura,et al.  Candela‐class high‐brightness InGaN/AlGaN double‐heterostructure blue‐light‐emitting diodes , 1994 .

[37]  Nelson Tansu,et al.  Approaches for high internal quantum efficiency green InGaN light-emitting diodes with large overlap quantum wells. , 2011, Optics express.

[38]  Armin Dadgar,et al.  GaN-based optoelectronics on silicon substrates , 2002 .