Ivana Kubicova

Structures patterning by non-contact NSOM lithography

This contribution presents experimental results from the fabrication of planar photonic structures with two-dimensional (2D) arrangement. We demonstrate the near-field scanning optical microscope (NSOM) lithography as an effective optical method for fabrication of 2D photonic structures in thin photoresist layer. We employ a non-contact mode of NSOM lithography using a metal coated fiber tip in combination with 3D nanoposition piezosystem. Prepared photonic structures in thin photoresist layer deposited on the GaAs substrate are analyzed by scanning probe diagnostics. Set of experiments was realized in order to improve the aspect ratio of the patterned structures, where the exposure time and the intensity of the exposing field were parameters.

Advanced optical methods for patterning of photonic structures in photoresist, III-V semiconductors and PMMA

This contribution presents experimental results in the field of planar two-dimensional (2D) photonic crystal (PhC) structures, as well as their design, fabrication and analysis. We demonstrate maskless optical methods leading to fabrication of 2D PhC structures for applications in optoelectronics. The 2D PhC structures of square and triangular symmetries with period from 275 nm to 2 μm were fabricated in thin photoresist layer, III-V semiconductor surfaces and polymethylmethacrylate using interference lithography and near-field scanning optical microscope lithography. The 2D PhC structures prepared in GaAs surface were used as a mold for nanoimprint lithography in polymethylmethacrylate.

Light emitting diode with 2D PhC structure in the surface analysed by NSOM

We present light emitting diode with two-dimensional photonic crystal structure prepared by interference lithography in the light emitting diode surface with an emission maximum at 845 nm. Applied two-dimensional photonic crystal structure improved light extraction efficiency for more than 30 %. The photonic crystal light emitting diode surface morphology was analyzed by atomic force microscope. The enhanced extraction efficiency of the photonic crystal diode was documented from L(I) dependencies from the near-field studies.

2D irregular structure patterning and analysis of LED by NSOM

This contribution presents possibilities of near-field scanning optical microscope (NSOM) in two different modes as an effective tool for semiconductor device surface patterning and for high-resolution microscopy. The illumination mode of the NSOM is used in lithography application to pattern two-dimensional irregular structure in the emitting surface of GaAs/AlGaAs-based light emitting diode (LED). The structure was patterned in the upper confinement AlGaAs layer and the enhancement of radiation from the patterned surface was proven by NSOM in collection mode.

Emission and absorption properties of patterned LED with 2D PhC

Photonic crystals (PhC) create platform for a new generation of optical and optoelectronical devices. The PhC structures have been patterned in GaAs-based light emitting diodes in order to modify their optical properties. Patterned diodes with two-dimensional PhC were investigated by measurements of emission and detection properties. Measured dependencies revealed effect of PhC on emission and photocurrent spectrum.

Irregular 2D structure in the light emitting diode surface patterned by NSOM lithography

In this paper, we present near-field scanning optical microscope (NSOM) in illumination mode as effective tool for semiconductor device surface patterning. In the illumination mode, the non-contact mode of the NSOM lithography is performed, where the fiber probe exposes defined spots in thin photoresist layer. As the scanning technique allows irregular two-dimensional patterning of different surfaces, this was applied on the GaAs/AlGaAs based light emitting diode surface. Patterned surface was analyzed by optical microscope and atomic force microscope.

2D photonic structure with square symmetry in the GaAs/AlGaAs LED surface

In this paper, effect of 2D photonic pattern on the emission properties of the GaAs/AlGaAs based light emitting diode (LED) emitting at wavelength of 850 nm is demonstrated. For LED surface patterning, the interference lithography based on a double-exposure process using two-beam interference method was used. The prepared photonic structure pattern in the LED surface was analyzed by atomic force microscope. Such prepared LED with 2D patterned photonic structure shows considerable enhancement of light extraction efficiency and improved far-field radiation pattern.