Investigation and correlation between surface modifications and field emission properties of laser-induced silicon plasma ion irradiated stainless steel

Abstract

Laser-induced silicon (Si) plasma has been used as a source of ion irradiation for modifications in surface, structural and field emission properties of Stainless Steel (SS). Nd:YAG (532 nm, 10 ns) laser at irradiance of 15 GW/cm² was used to generate Si-plasma ions which were detected by solid-state nuclear track detector (CR-39) and Faraday Cup (FC). Both the energy and fluence of Si ions were measured by FCs. In response to a stepwise increase in the number of laser pulses from 3000 to 12000, the ion fluence varies from 4.6 × 10¹⁴ to 18.3 × 10¹⁴ ions/cm² with constant energy of 30 keV. Fourier Transformation Infrared (FTIR) spectroscopy analysis revealed that irradiated silicon makes the stretch band with oxygen Si–O–Si. X-Ray Diffraction (XRD) analysis confirmed the identification of new phase of Si (111) with an anomalous trend in crystallite size, dislocation line density and induced stresses in response to the irradiation with various Si ion fluences. Optical microscopy analysis showed the formation of pits, voids and tracks. Scanning electron microscope (SEM) analysis revealed the formation of nanoscale surface features including pores, craters, embedded particulates and protruded disk-like structures with multiple ablative layers at the fluence of 4.6 × 10¹⁴ to 13.7 × 10¹⁴ ions/cm². At the highest ion fluence of 18.3 × 10¹⁴ ions/cm², the flake/flower-like morphology is observed. Field emission (FE) properties were studied under ultra-high vacuum condition in a parallel plate configuration using planar virgin SS as an anode and structured SS as a cathode. The Fowler–Nordheim plots were obtained from I–V characteristics to evaluate the turn-on field, field enhancement factor β and a maximum current density ranging 1.5–4.5 V/µm, 5008–12807 and 96–454 nA/cm2, respectively. The variation in the FE properties is attributed to the different morphological features at varying silicon ion fluences.

KEYWORDS:

• Ion irradiation
• surface structures
• thermal spike model
• field emission properties
• laser-induced plasma ions

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Rizwan Amir

Rizwan Amir did his Mphil Applied Physics from Center for Advanced Studies in Physics Government College University Lahore, Pakistan. He worked on the project Investigation of surface modifications and field emission properties of Si ion implanted Stainless Steel.

Shazia Bashir

Shazia Bashir is working as Director/Professor (Physics) at Centre for Advanced Studies in Physics, Government College University Lahore, Pakistan. She received her PhD degree from Technical University Vienna Austria in 2010. She has 26 years of post-graduate teaching/research experience. Her field of specialization is laser-matter interaction. She has published 111 international research papers with total impact factor of 320. She has supervised more than 100 graduate and post graduate students.

Mahreen Akram

Mahreen Akram received MPhil (Physics) and PhD (Physics) degrees in 2011 and 2018 respectively from Government College University Lahore. She visited Institute of Applied Physics, Vienna University of Technology (TU WIEN), Austria in 2016 to perform a part of her PhD research work. She joined GCU Lahore as a lecturer of physics in year 2010 and currently working as an Assistant Professor. Her areas of interest include laser and ion irradiation induced material processing specially for field emission applications and laser induced plasma diagnosis. She has authored and contributed in more than 45 international impact factor journal publication.

Muhammad Shahid Rafique

Muhammad Shahid Rafique is working as Dean of Natural Sciences/Professor (Physics) at University of Engineering and Technology Lahore, Pakistan since last 7 years. He is serving this institute since last 21 years. He received his PhD from Nan Yang Technological University Singapore in 2000. He has more than 250 research publication in his credit. He has produced more than 200 graduate students in the field of laser matter interaction, Plasma Physics and materials sciences.

Mubashir Javed

Mubashir Javaid is working as PhD scholar at Centre for Advanced Studies in Physics, Government College University Lahore, Pakistan. He is working on SELF generated electric and magnetic field measurement of metallic correlated with plasma parameters.

Khaliq Mahmood

Khaliq Mahommod has been working as Assistant Professor at Centre for Advanced Studies in Physics, Government College University Lahore, Pakistan since last 16 years. He did his PhD Government College University Lahore. He has more than 46 publications to his credit.

Wolfgang Husinsky

Wolfgang Husinsky is working as Professor of Physics at Institute of Applied Physics Technical University Vienna Austria. He has hundreds of Publications in well reputed journals his credit. He has supervised more than 200 students.

Shahzeb Ahmad

Shahzeb Ahmad did his MPhil Applied Physics from Center for Advanced Studies in Physics, Government College University Lahore, Pakistan. He worked on laser and ion-induced structuring of materials with special emphasis on enhancement of Field Emission properties.