DOI: 10.5281/zenodo.17424222
title: Dataset for Insulator material deposited with Molybdenum disulphide prospective for sensing application

description: The primary target of molybdenum disulfide (MoS2) crystal 99.995 % with a size of about 0.5 cm × 1.0 cm × 0.2 mm and a density of 5.06 g/cm3 at 15 °C has been purchased from Sigma Aldrich. 

The deposition of the adopted insulators occurred in a vacuum of about 7.6·10-3 mbar inside a vacuum chamber. A Q-switching Nd: YAG laser operating at a wavelength of 1064 nm, a pulse duration of 5 ns, was used at a repetition rate of 10 Hz and 30 minutes of irradiation time. The laser beam passed through a 50 cm lens to focus the beam to a diameter of 0.5 mm on a solid target of MoS2 placed in a rotating carrousel to avoid deep ablation which could modify the laser density. A fresh target surface was always exposed to the incident laser light. 

The distance between the window of incoming laser and the target is of 22 cm. The volume of the vacuum chamber is about 52 liters. The energy of the laser pulse was 600 mJ and the laser incidence angle was 45° on the surface of the target corresponding to a laser fluence of about 76 J/cm2. When the laser fluence overcame the ablation threshold of the MoS2, ions, besides other particles, atoms, and clusters, were ejected.

A Tencor P-10 has been employed as a surface profiler to measure the crater size and shape formed on the surface of the MoS2 after one laser shot to evaluate the amount of removed material during the laser irradiation.

A mass quadrupole spectrometer QMG F3 220 PrismaPlus (MQS) from Pfeiffer Vacuum was used to detect the emitted atoms and molecules from the laser ablation of a target of MoS2 in vacuum. Typically, the spectrometer detects the emission of the gas produced in the vacuum chamber. This spectrometer detects masses ranging between 1amu and 300 amu, with a sensitivity lower than 1 ppm and a mass resolution better than 1 amu. The MQS is equipped with a SEM detector with a power supply of 1100 V. The masses of interest have been selected as follows: 18 (H2O), 32 (S), 48 (SO), 64 (S2), 96 (Mo), 112 (MoO), 128 (MoS), 160 (MoS2) amu. The MQS detects the emitted atoms and molecules as a function of the time at the laser switching on and 1 Hz laser repetition rate. 

The Attenuated Total Reflectance – Fourier Transform Infrared (ATR-FTIR) spectroscopy using a Jasco 4700 and UV-VIS spectroscopy by means a Jasco V750 spectrophotometers, have been employed to analyze the alteration of the presence of specific functional groups, the changes of the chemical structure and of the optical transmittance in the polymer after the deposition of MoS2. 

The control of the quality of the deposited MoS2 has been explored by Atomic Force Microscope (AFM) analysis. The accomplishment of the surface average roughness (Ra) and the mean roughness parameter (RMS) was performed using a Dimension ICON- Bruker Corp. has been used. The 3D images with scan size of 1 mm have been captured using an exposure time of 1s, and processed by NanoScope Analysis software. 

The monitoring of the electrical capacitance alteration was performed by the I–V characteristic curve through frequency dependence measurements of the output voltage of a high-pass filter at the constant current of 0.5 mA for pristine samples and 0.1 mA . A metallic mask containing two stripes at distance of 1 mm each other and width of 10 mm was used to assist the production of two gold electrodes 50 nm thick sputtered on the composite surface. The resistivity of the used resistor was 1 MW. The voltage response was recorded over frequencies ranging between 20kHz and 100 kHz.

The alternating current (AC) with sinusoidal waveform was generated using a Keithley 6221 current source. The AC voltage vs frequency was monitored by a Tektronix TDS5104B. oscilloscope. Commercial ceramic capacitor of 2.6 pF. 6.8 pF and 12 pF have been used to display the corresponding voltage frequency. In the experimental configuration shown in Figure 2 the prepared composite or the used commercial ceramic capacitor are alternatively positioned.