3D nanohole arrays generated by spherical-lens photolithography

Abstract We demonstrate an applicable 3D nanohole array comprising pore shape with circular upper opening and sexfoil-shaped bottom, which is obtained by designing the appropriate ratio of the illumination wavelength and the diameter of colloidal nanosphere in combination with the proper photoresist thickness during the photolithography process. A photoresist film with the 3D nanoholes is employed as a physical mask to etch sapphire substrates. LEDs grown on the nanopatterned sapphire substrates deliver 44.3% enhancement in light output power compared to that of LEDs grown on flat sapphire substrates.