Arbitrary surface structuring of amorphous silicon films based on femtosecond-laser-induced crystallization

Abstract

Aluminum-induced crystallization of amorphous silicon on glass substrates above and below the eutectic temperature Appl.The arbitrary surface structuring of amorphous silicon ͑a-Si͒ films was performed by applying the Fourier-transform ͑FT͒ method to the femtosecond-laser-induced crystallization. In order to realize the arbitrary structuring, the logo q-Psi was produced in the a-Si film by the FT of a computer-generated hologram. The crystallization of a-Si was performed using the near-infrared femtosecond-laser pulses. By micro-Raman spectroscopy, scanning-electron microscopy, and transmission-electron microscopy, it was found that the femtosecond-laser pulses induced a localized phase transformation from the amorphous to the crystalline phase, and the spatially selected crystallization of the a-Si was responsible for the formation of the two-dimensional pattern.

Photoactivation of silicon quantum dots

“…In the case of CdSe QDs, photoactivation experiments showed an order-of-magnitude increase in the PL intensity and an ability to write the activated dots into ''letters'' [43,44]. For Si-QDs, previous efforts toward luminescence patterning used a high-intensity laser to locally anneal an SiO x film [30]. Here, we demonstrate that similar potential exists for free-standing Si QDs, using photoactivation.…”

“…Using a combination of FTIR and electron spin resonance (ESR) spectroscopic data Lee et al [29] drew the conclusion that laser irradiation breaks any silicon-hydride bonds present on the Si surface, causing the formation of neutral P b centers [30]. No evidence for the formation of Si-O surface bonding was presented.…”

Femtosecond laser irradiation-induced infrared absorption on silicon surfaces

“…Therefore, as the pulse number or pulse energy increases, the NIR absorptance decreases after reaching a maximum value. The silicon amorphous structure goes back to silicon crystalline structure under the influence of laser irradiation [15][16][17][18][19][20][21][22][23][24][25][26]. The silicon structure can be changed back and forth between crystalline and amorphous by controlling the experimental conditions.…”

“…On the one hand, amorphous silicon-related papers of laser irradiation mainly concentrated on the application of the laser-annealing effect, i.e., amorphous silicon became silicon crystalline or micro/nanostructured silicon for better optoelectronics applications [15][16][17][18][19][20][21][22][23][24][25][26]. On the other hand, amorphous silicon and lattice distortions could be formed with the femtosecond laser irradiation [27][28][29][30][31].…”

Giant birefringence and dichroism induced by ultrafast laser pulses in hydrogenated amorphous silicon

“…21 Transforming amorphous silicon (a-Si) into a nanocrystalline form through ultrafast laser irradiation has already been demonstrated (nc-Si). [22][23][24][25][26][27][28][29][30][31] In this letter, we demonstrate that the ultrafast laser assisted nanocrystallization of a-Si:H is accompanied by the formation of a laserinduced periodic structure. The observed pattern with the subwavelength modulation of the complex refractive index exhibits a dichroism and enhanced form birefringence, which is two orders of magnitude higher than commonly observed in uniaxial crystals such as quartz, ruby, sapphire, or femtosecond laser nanostructured silica glass.…”