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Amorphous carbon (a-C) film is a unique material that attracts the attention of scientists to be investigated. Nitrogen- and boron- doped amorphous carbon (a-C:N and a-C:B) have been deposited on ITO glass substrates by using nanospray method. Palmyra sugar is heated at temperature 250o C for 2.5 hours to obtain a-C. Boric acid (H3BO3) and amonium hidroxide (NH4OH) are used as the sources of boron doping and nitrogen doping. a-C:N and a-C:B are made by the variations of mole ratio for doping and amorphous carbon, that are 1:15 and 1:20. Then, these samples are dissolved into mixed dymethyl sulfoxide (DMSO) and aquades. The exfoliation process of samples has been done by applying ultrasonic cleaner for 2 hours and also centrifugated at 4000 rpm for 45 minutes. Electrical conductivity and band gap are measured by using four point probe and UV Vis. The results show that electrical conductivity increases but band gap decreases than pure a-C. Furthermore, the larger mole ratio of a:C-N and a-C:B also increases conductivity and decreases band gap, resulting between 5.5×10-1S/cm – 6.1×10-1 S/cm and 1.43 eV – 1.71 eV.

Structure of amorphous carbon can be composed of sp2 (graphite), or sp3 (diamond), or a combination of both, depending on their fractions. Therefore, many researchers were exploring to use it as solar cell material. This research used the amorphous carbon of bio-product as a basic material in the form of palmyra sugar which was synthesized through the heating and doping process to produce n-type and p-type semiconductors. This research aims to analyze the effect of dopant and deposition time on electrical properties. The heating process was carried out at 250°C and the doping process was carried out by adding NH4OH for a-C:N and H3BO3 for a-C:B. The deposition process was carried out by the nano-spray method using a variety of deposition time on the ITO substrate. The result of scanning electron microscopy (SEM) showed that the film thickness increased with the increase of deposition time. Besides, the result of four-point probe (FPP) showed that the dopant can increase electrical conductivity, but the film thickness did not influence it. The electrical conductivity obtained was 5x10-1 - 6x10-1 S/cm. And the result of further analysis, it can be concluded that electrical conductivity was still in the range of semiconducting material.

Amorphous carbon films have been explored and used in a wide variety of applications. With the n-type and p-type amorphous carbon film, it can be used to make p-n junctions for solar cells. This research aims to study the structure of boron- and nitrogen-doped amorphous carbon (a-C:B and a-C:N) films. This research uses the basic material of bio-product from palmyra sugar to form amorphous carbon. Amorphous carbon was synthesized by heating the palmyra sugar at 250°C. The results of XRD showed that the doped films produce an amorphous carbon phase. PES was used to analyze the bonding state of dopants in the sample. B4C, BC3, and BC2O bonds formed in a-C:B, while pyridine and pyrrolic formed in a-C:N.

The purpose of this study is to determine the effect of heating temperature and the chemical exfoliation process on the reflection loss of r-GO synthesized from coconut shell. The heating process is carried out at temperature of 400°C and 700°C. The chemical exfoliation process is carried out by adding 1M H2SO4 solution in a ratio of 1: 1, 1: 5, and 1:10. Then, the process of washing is done using an ultrasonic cleaner. The XRD pattern indicates that coconut shell charcoal has formed the r-GO phase. In the chemical exfoliation process with the addition of 1M H2SO4 solution in a ratio of 1: 10 at a temperature of 400°C, it shows that the maximum reflection loss is -7.186 dB at 10.48 GHz with an electrical conductivity of 1.075 x 10-3 S/cm.