Submicrometre periodic surface structures in InP induced by nanosecond UV laser pulses

Abstract

We report fabrication of submicrometre size laser-induced periodic surface structures (ripples) on single crystalline InP by nanosecond (ns) pulsed Nd : YAG laser beam irradiation of fourth harmonic wavelength (266 nm) in HF electrolyte. The ripples are orientated parallel to the laser polarization direction and power spectral density analysis reveals reduction in the spatial period of the ripples with increasing number of laser shots. The formation of periodic structures in the presence of electrolyte is empirically explained on the basis of photoelectrochemical etching and variation of periodicity with refractive index change on laser energy and number of laser pulses. From the analysis of energy dispersive x-ray, photoluminescence (PL) and micro-Raman spectroscopy measurements on the rippled surface we conclude that the ripple structures are capped with a thin layer of In2O3. Further, a blue shift of 0.328 eV compared with the band-edge luminescence of InP is estimated from the PL spectrum of the structure fabricated with 200 laser shots. The blue shift of the PL peak is attributed to the quantum confinement effect in the nanometre size structures in the rippled surface. Micro-Raman spectra show good crystalline quality of the surface at lower number of laser shots and its degradation caused by oxidation at the higher number of shots.

Multiphoton excitation of surface plasmon-polaritons and scaling of nanoripple formation in large bandgap materials

“…From this time, the phenomenon of self-organized structure formation was observed on surfaces of various kinds of solid materials such as metals [2], semiconductors [3,4], dielectrics [5], ceramics [6,7], and polymers [7,8]. The laser-material interaction giving rise to these effects requires laser pulses of appropriate energy, intensity and wavelength and depends on the number of pulses, pulse duration and shape, repetition frequency and the polarization state of the laser field.…”

Fabrication of Silicon Surface Grating Structures by Maskless Laser Beam Lithography

“…The fundamental spatial frequency 0.92 m −1 is estimated from the PSD plot of grating structures fabricated with number of laser pulses of 600 and 900 which corresponds to the periodicity of 1106 nm, and the fundamental spatial frequency 0.90 m −1 is estimated for 1500 laser pulses which correspond to the periodicity 1086 nm. The decrease in periodicity with increasing number of laser pulses is not clear but it is similar to the observed reduced periodicity in laser induced periodic structures in glass and InP with increasing the number of laser pulses [11][12][13]. Lowering of periodicity from 1106 nm to 1086 nm with number of laser pulses points toward possible increase in refractive index due to nonlinear processes which may reduce the plasma generation or free electron density upon further laser pulses irradiation.…”

Submicron and nano surface patterning using nanosecond laser technique

“…It may be can explains similar to interference between the laser beams and the scattered beam on the substrate; so surface roughness and in-homogeneity caused surface waves, freezing of capillary waves and generation of a temporary periodic heating pattern during laser irradiation. These waves serve as the starting in-homogeneity of the absorptivity of the surface, as consequence of processes [43,77,78]. Take into consideration the fact that (FCW) period (A) cannot exceed the life time of the liquid layer 'tL.…”