Electrical Properties of Photodiode Ba_0.25Sr_0.75TiO₃ (BST) Thin Film Doped with Ferric Oxide on p-type Si (100) Substrate using Chemical Solution Deposition Method

Abstract

In this paper we have grown pure Ba 0.25 Sr 0.75 TiO 3 (BST) and BST doped by Ferric Oxide Fe 2 O 3 (BFST) with doping variations of 5%, 10%, and 15% above type-p Silicon (100) substrate using the chemical solution deposition (CSD) method with spin coating technique at rotation speed of 3000 rpm, for 30 seconds. BST thin film are made with a concentration of 1 M 2-methoxyethanol and annealing temperature of 850 O C for the Si (100) substrate. Characterization of the thin film is performed for the electrical properties such as the current-voltage (I-V) curve using Keithley model 2400 as well as dielectric constant, time constant, pyroelectric characteristics, and depth measurement. The results show that the thin film depth increases if the concentration of the Ferric Oxide doping increases. The I-V characterization shows that the BST and BFST thin film has photodiode properties. The dielectric constant increases with the addition of doping. The maximum dielectric constant value is obtained for 15 % doping concentration namely 83.1 for pure BST and 6.89, 11.1, 41.63 and 83.1, respectively for the Ferric Oxide doping based BST with concentration of 5%, 10%, and 15%. XRD spectra of 15 % of ferric oxide doped BST thin film tetragonal phase, we carried out the lattice constant were a = b = 4.203 Å; c = 4.214 Å; c/a ratio = 1.003.

The Effects of Lanthanum Dopant on the Structural and Optical Properties of Ferroelectric Thin Films

“…As expected from our previous work [9], we observe a decrease in the lattice parameter of La-doped BST thin films (BSLT) compared to nondoped thin films which were 3.936 and 3.949 Å, respectively. The reason for this decrease is due to the insertion of La atoms as substitutes in the BST lattice.…”

“…This method is based on deposition of chemical solution on the top of a substrate often followed by rotation at certain rotational speed using spin coating. Several advantages of using CSD are as follows: processing temperature can be relatively low, composition homogeneity is achieved, precise control of the composition, as well as large area deposition [9][10][11].…”

“…Meanwhile, the average surface roughness for BGST thin films were 0.632, 0.564, and 0.487 nm at annealing temperature of 200, 240, and 280°C, respectively, whereas the grain sizes (mean diameter) were 238.4, 219.0, and 185.1 nm, respectively. The average surface roughness for BTST thin films were 1.087, 0.4870, and 0.2317 nm at temperature 200, 240, 280°C, respectively, whereas the grain size (mean diameter) are 158.7, 291.1, and 396.7 nm, respectively [9]. Thus, we found that addition of dopants significantly alters the surface roughness and grain size, and a similar feature is expected for rare-earth, e.g., lanthanum oxide (La 2 O 3 ) dopant on thin films.…”

“…Barium strontium titanate (Ba 0.5 Sr 0.5 TiO 3 -BST) was produced by using the chemical solution deposition (CSD) method with ultrasonic mixing of 0.160 g barium acetic + 0.131 g strontium acetic + 0.355 g titanium isopropoxide + 0.060 g gallium oxide as a precursor [9] .99%] with 2.5 ml of 2-methoxy ethanol as a solvent, a BST solution was obtained. The barium strontium titanate (BGST) thin films were fabricated also via CSD methods with ultrasonic mixing of 0.160 g barium acetic + 0.131 g strontium acetic + 0.355 g titanium isopropoxide + 0.060 g gallium oxide as a precursor in 1.25 ml 2-methoxyethanol solution for 2 h. Meanwhile, barium strontium titanate (BTST) was produced with the same method using 0.160 g barium acetic + 0.131 g strontium acetic + 0.355 g titanium isopropoxide + 0.060 g tantalum oxide as a precursor in 1.25 ml 2-methoxyethanol as solvents.…”

“…Before we explain the effect of lanthanum on barium strontium titanate (BST), we first describe our earlier works regarding the effect of the addition of nonrare earth-dopant BST because one can compare the results to similar treatment of substrates with lanthanum dopant [9].…”