nan Irzaman

The Effect of Ba/Sr Ratio on Electrical and Optical Properties of BaxSr(1-x)TiO3 (x = 0.25; 0.35; 0.45; 0.55) Thin Film Semiconductor

Ferroelectric BaxSr(1-x)TiO3 thin film semiconductors with Ba/Sr ratio deposited on silicon using chemical solution deposition (CSD) method have been investigated, followed by annealing at 850°C for 15 hours. Observations by I-V meter, LCR meter, and oscilloscope were employed to characterize the electrical properties of the thin films and the observation of fourier transform spectroscopy (FTIR) and particle size analyzer (PSA) to characterize the optical properties. The results showed that the dielectric constant was given around 2–18. Moreover the obtained films were found to be resistor because the I-V graph of each sample was ohmic either in dark or bright environment. The increase of BST mol fraction at dark environment is proportional to the increase of the curve slope. While at bright environment gives the highest curve slope for BST with fraction x = 0.45. Based on electrical conductivity of thin films, we conclude that the thin films are semiconductor. Moreover, functional group and particle size of sample were analyzed using FTIR and PSA analyzer. The augmentation of Ba would decrease the transmittance band of OH− and increase the transmittance band of C-O because the radius of Ba is higher than Sr. The particle distribution size of BST 0.45 is 134.93 nm smaller than BST 0.25 which gives 186.26 nm, BST 0.35 gives value of 467.86 nm and BST 0.55 is 407.49 nm.

Optical Properties of Crystalline Ta2O5 Thin Films

Thin tantalum oxide (Ta 2 O 5 ) films were prepared on Si(100) substrates using the chemical solution deposition (CSD) method. X-ray diffraction (XRD), scanning electron microscopy (SEM), spectrophotometric UV-VIS and ellipsometric measurements were employed to characterize these films. High-quality films of Ta 2 O 5 were obtained by spin coating at 2000, 2250, 2500, 2750 and 3000 rpm during 30 s, and subsequently annealed at 900°C for 15 h. The microstructure and crystallinity of the thin films were analyzed by XRD in preferred (001), (010), (200) orientations, the surface morphology was examined by SEM, and the film thickness was determined by profilometric and ellipsometric measurements, the thin films were heterogeneous. The orthorhombic structure and crystallinity of Ta 2 O 5 thin films on Si(100) substrates were characterized by XRD. The obtained lattice constants are a = 6.117 A, b = 3.716 A, c = 4.114 A. The optical spectrophotometric measurements at λ = 400 nm yielded refractive index values n of 1.81-1.93; from ellipsometric analysis the refractive index values are 1.8-1.94.

Application of lithium tantalate (LiTaO3) films as light sensor to monitor the light status in the Arduino Uno based energy-saving automatic light prototype and passive infrared sensor

ABSTRACT Growth of LiTaO3 film on a type-p silicon substrate (100) was conducted using the Chemical Solution Deposition (CSD) and spin coating methods at a speed of 3000 rpm for 30 seconds. The film on the substrate was then heated at 850oC for 15 hours. The resulting film was then characterized for its sensitivity value. The film was utilized as a light sensor to read changes in light intensity to monitor lighting status in an Arduino Uno-based energy-saving automatic light prototype. Previously, the output of the film in the form of an electrical voltage was strengthened using a voltage amplifying circuit (OP-Amp). The energy-saving automatic light prototype was manufactured in two conditions, an automatic condition (with assistance from an infrared passive sensor and real time clock) and a manual condition (with assistance from a GSM to control the lighting and LiTaO3 film as a light sensor to monitor the lighting status). In the automatic condition, the assessment of the infrared passive sensors sensitivity was conducted at distances of 0 m, 0.5 m, 1 m, 1.5 m, 2 m, 2.5 m, and 3 m at angles of 00, 300, 450 and 600 (the source of motion was human movements). The real time clock was used to regulate the infrared passive sensor activation time (7 a.m to 5 p.m Western Indonesia Time). In the manual condition, when entering manual time (outside the 7 a.m to 5 p.m Western Indonesia Time range), to be exact, the GSM would send a message containing the duration of the lighting usage and the cost of the lighting usage. Activation of the lighting was conducted by replying to the message with the code #1 to turn on the lighting and #0 to turn it off.

The optical band gap of LiTaO3 and Nb2O5-doped LiTaO3 thin films based on Tauc Plot method to be applied on satellite

This research observed the optical band gap of thin films made from LiTaO3 undoped (0%) and doped (5% and 10%) with Nb2O5 in the 1 M-solubility deposited on n-type Si (111) substrates. The thin films are manufactured with coating process of substrates by Chemical Solution Deposition (CSD) method using a spin coater device at a rotation speed of 3000 rpm for 30 seconds and annealed in furnace (Nabertherm B180) at a temperature of 850°C for 15 hours. The optical absorption data of thin films are obtained by using an Ocean Optics USB2000 device in the wavelength of visible light. The band gap curve is determined from optical absorption data processing using Tauc Plot method. The Tauc Plot with indirect transition shows that LiTaO3 doped with Nb2O5 provides increased optical band gap value in a range less than 3.5 eV. Based on the results of this research, it can be concluded that LiTaO3 and Nb2O5-doped LiTaO3 thin films on n-type Si (111) substrate are semiconductor materials and has the potential to be applied on satellite.

The effect of annealing temperature variation on the optical properties test of LiTaO3 thin films based on Tauc Plot method for satellite technology

The purpose of the present research is to observe the energy gap of thin films made from LiTaO3 in 1 M-solubility deposited on n-type Si (111) substrates with annealing temperature variation. The manufacture of thin films has been formed by Chemical Solution Deposition (CSD) method using spin coater on 3000 rpm speed for 30 seconds and performed annealing process using furnace (Nabertherm type B180) at a temperature of 750°C, 800°C and 850°C for 15 hours. The absorbance of thin films is measured by using an Ocean Optics USB2000 device and processed into the energy gap curve using Tauc Plot method. The result shows that the energy gap of thin films associated with indirect transitions are increased from 2.78 eV to 2.93 eV with the rise of annealing temperature. The research shows that the thin films on n-type Si (111) substrates made of LiTaO3 produces sensitivity to violet light spectrum and have the potential to be developed as a sensor on satellite technology.

Barium Strontium Titanate Thin Film Growth with rotational speed variation as a satellite temperature sensor prototype

Barium Strontium Titanate(BST) is a promising material for sensor devices such as temperature and infrared sensor. BaxSr1-xTiO3 thin films with affordable Si substrate were prepared by chemical solution deposition method and spin coating technique for 30 seconds with variation in rotation speed (3000 rpm, 5500 rpm and 8000 rpm). A high baking temperature at 8500C has been used for 15 hours during the annealing process. The thickness of BST film was calculated via gravimetric calculation. USB 2000 VIS-NIR was used to characterize the optical properties of BST thin film. The obtained reflectance curve showed that the most reflected wavelengths were in the range of 408-452 nm respectively. The result of the optical film characterization is very important for further development as a sensor in satellite technology.

Manufactures and Characterizations of Photodiode Thin Film Barium Strontium Titanate (BST) Doped by Niobium and Iron as Light Sensor

Pure Ba0,5Sr0,5TiO3 (BST) thin film, BST doped by niobium (BNST) and BST doped by iron (BFST) have been synthesized on p‐type Si (100) substrates using Chemical Solution Deposition (CSD) methods followed by spin coating and annealing techniques. Current‐voltage characterizations on these sample result in agreement that all of the BST, BNST, and BFST thin films have photodiode properties. Electrical conductivity values of BST, BNST, and BFST are in the range of conductivity values of semiconductor materials. Niobium or iron doping on the BST samples increase their conductivity value their dielectric constant. This conductivity values may change when a light is exposed on the film surface. Absorbance and reflectance characterizations show that the BST, BNST, and BFST thin films absorb certain range of visible and infrared light. It is convincing that the BST, BNST, and BFST thin films might be used as photodiode light sensor.

Development of Luxmeter Based on Ba0,25Sr0,75TiO3 Ferroelectric Material

Ba0,25Sr0,75TiO3 (BST) thin films has been deposited on a Si (100) p‐type substrate by chemical solution deposition (CSD) method followed by spin coating technique (at 3000 rpm rotational speed for 30 seconds) and annealing process at the temperature around 850° C for 15 hours. The films show a maximum optical absorption at green light. An I–V investigation on the films results in agreement that the thin films have a photodiode characteristic. Electrical conductivity of the BST thin films is in the range of 2.79×10−7 to 5.3×10−7 S/cm, it is the range of semiconductor materials. The electrical conductivity and photocurrent increase when the light intensity increases from 1000 to 6000 Lux. A BST thin film has been utilized as a light meter in an ATMega8535 microcontroller since it is sensitive with a light intensity change. Base on calibration and validation curves, a measurement using this microcontroller results in comparable light intensity values with that result from a standard instrument.

Modified Spin Coating Method for Coating and Fabricating Ferroelectric Thin Films as Sensors and Solar Cells

Spin coating process with a modified spin coater is performed well, especially the second generation of modified spin coater, which has a maximum value of 18,000 rpm, is able for manufacturing/coating photonic crystal‐based ferroelectric thin films that require a high angular velocity (rpm). Ferroelectric thin films that use both 3000 and 6000 rpm have given good results in energy gap, electrical conductivity, etc. In addition, the modified spin coater has also produced several applications such as sensors in the device of blood sugar level noninvasively, sensors in the automatic drying system, sensors in the robotic system, and photovoltaic cells in the system of solar cells/panels which are being developed at present. These applications used ferroelectric material such as barium strontium titanate (BST), lithium niobate (LiNbO3), cuprous oxide (CuO), and lithium tantalate (LiTaO3).