• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.2
• /
• pp.133-137
• /
• 1998

$(Pb_{0.72}La_{0.28})Ti_{0.93}O_3(PLT(28))$ thin films were fabricated by pulsed laser deposition. PLT films deposited on $Pt/Ti/SiO_2/Si$ at $600^{\circ}C$ had a preferred orientation in (111) plane and at $550^{\circ}C$ had a (100) preferred orientation. We found that (111) preferred oriented films had well grown normal to substrate surface. This PLT(28) thin films of $1{\mu}m$ thickness had dielectric properties of ${\varepsilon}_r$=1300, dielectric $loss{\fallingdotseq}0.03 $. and had charge storage density of 10 [${\mu}C/cm^2$] and leakage current density of less than $10^{-6}[A/cm^2]$ at 100[kV/cm]. These results indicated that the PLT(28) thin films fabricated by pulsed laser deposition are suitable for DRAM capacitor application.

• Journal of Sensor Science and Technology
• /
• v.5 no.3
• /
• pp.87-92
• /
• 1996

The PLT thin films on (100) cleaved MgO single crystal substrate have been fabricated by rf magnetron sputtering using a PbO-rich target. The dependence of physical and electrical properties on the degree of c-axis orientation has been studied. The degree of c-axis orientation of PLT thin films depends on fabrication conditions. Fabrication conditions of the PLT thin films were such that substrate temperature, working pressure, gas ratio of $Ar/O_{2}$, and rf power density were $640^{\circ}C$, 10 mTorr, 10 seem, and $1.7\;W/cm^{2}$, respectively. In these conditions, the PLT thin film showed the Pb/Ti ratio of 1/2 at the surface, the resistivity of $8{\times}10^{11}{\Omega}{\cdot}cm$, and dielectric constant of 110. The pyroelectric infrared sensors with these PLT thin films showed the peak to peak voltage of 450 m V and signal to noise ratio of 7.2.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.39 no.10
• /
• pp.35-42
• /
• 2002

Modulation frequency dependences of the pyroelectric properties of PLT (P $b_{1-x}$ L $a_{x}$ $Ti_{1-x}$ 4/ $O_3$) thin films with La concentrations of 5, 10 and 15㏖% have been investigated by using the dynamic method. The PLT thin film with 10㏖% of the La concentration (PLT(10) thin film) shows the most excellent pyroelectric properties among the films. For PLT(10) thin film, the pyroelectric coefficient shows the maximum value of 6.6$\times$10$^{-9}$ C/$\textrm{cm}^2$ㆍK without frequency dependence. The figure of merits for the voltage responsivity and specific detectivity are 1.03$\times$10$^{-11}$ Cㆍcm/J and 1.46$\times$10$^{-9}$ Cㆍcm/J, respectively. Voltage responsivity corresponding to the pyroelectric voltage is almost constant at low modulation frequency and decreases in proportional to frequency at high modulation frequency. Voltage responsivity is 5.15 V/W at 8Hz. Noise equivalent power (NEP) and specific detectivity ( $D^{*}$) of the PLT(10) thin film are 9.93$\times$10$^{-8}$ W/H $z^{1}$2/ and 1.81$\times$10$^{6}$ cmH $z^{1}$2/W at the frequency of 100Hz, respectively. The results indicate that PLT(10) thin film is very suitable for pyroelectric IR sensors.s.s.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1997.11a
• /
• pp.48-51
• /
• 1997

(Pb. La)TiO$_3$ thin films were fabricated by sol-gel Processing and spin-coated on the Pt substrate. The spin-coated PLT films were sintered at 75$0^{\circ}C$ for 5min by rapid thermal ann La content dependence of the electrical properties of the PLT thin films are discussed. Wit La mole% from 20 to 36mo1e%. the dielectric constant of the PLT thin films decreased f 570. P-E hysteresis loops changed from ferroelectric to paraelectric. and the charge storage charging time decreased. The Curie Point decreased with increasing La content. The leak density also decreased and La 36mo1% species shows mood characteristics less than 10- electric field 500 (KV/cm) Because of the broad range of composition-controlled ferroelectric PLT thin films are suitable for memory application.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.12 no.5
• /
• pp.247-252
• /
• 2002

$(Pb_{1-x}La_x)TiO_3$ (x = 0.1) thin films were prepared on ITO-coated glass substrates by metal organic chemical vapor deposition using ultrasonic spraying. Effects of the post-annealing and the seeding layer on crystallization, microstructures and electrical properties of thin films were investigated. Dielectric constants of films increased due to the modification of crystallization and the changing of a surface morphology by applying the post-annealing. In addition, as the application of PT seed- ing layer offered nucleation sites to PLT thin films, electrical properties of films were enhanced by the increase of crys-tallinity and grain size. The dielectric constant of the films post-heated for 60 min and with a seeding layer was 213 at 1 kHz.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.33A no.2
• /
• pp.87-95
• /
• 1996

We have studied the effects of La concentration on the optical and electrical properties of lead lanthanum titanate (PLT) thin films by using sol-gel method. Both the optical and electrical properties are greatly affected by the La concentration. The refreactiv eindices of the films varied from 2.23 to 1.93 with varying La concentration in the range from 15 to 33 mol%. The dielectric constants of the films vary form 340 to 870 with varying La concentration in the range form 15 to 33 mol%. Hysteresis loop becomes slimmer with the increase of La concentration form 15 to 28mol% and little fatter again with the increase of La concentration form 28 to 33 mol%. Among the films investigated in this research, PLT(28) thin film shows the best dielectric properties for the application to the dielectrics of ULSI DRAM's. At the frequency of 100Hz, the dielectric constant and the loss tangent of PLT(28) thin films are 940 and 0.08 respectively. Its leakage current density at 1.5${\times}10^{5}$V/cm is 1${\times}10^{-6}A/cm^{2}$. The comparision between the simulated and the experimental curves for the switching transient characteristics shows that PLT (28) thin films behaves like normal dielectrics.

• Electrical & Electronic Materials
• /
• v.11 no.10
• /
• pp.53-59
• /
• 1998

Paraelectric lead landthanum titanate(PLT) thin films have been prepared by a reactive dc magnetron sputtering system using a multicomponent metal target. The surface area control of each element on the target markedly facilitates the fabrication of thin films of complex ceramic compounds. A postdeposition heat-treatment was applied to all as-deposited PLT thin films at annealing temperatures up to 75$0^{\circ}C$ for crystalization. The composition of the PLT(28) thin filmannealed at $650^{\circ}C$ was: Pb, 0.73; La, 0.28; Ti, 0.88; O, 2.9. The dielectric constant and dissipation factor of the thin film(200 nm) at low filed measurements (500 Vcm-1) are 1216 and 0.018, respectively. The charge storage density using a typical Sawyer-Tower circuit with a 500 Hz sine wave was 12.5 $\mu$Ccm-2 at the electric field of 200 kVcm-1.

• Journal of Sensor Science and Technology
• /
• v.6 no.3
• /
• pp.188-193
• /
• 1997

The lanthanum-modified lead titanate (PLT) thin films on (100) cleaved MgO single crystal substrate have been prepared by RF magnetron sputtering method using PbO-rich target with varing La contents. The substrate temperature, working pressure, $Ar/O_{2}$, and RF power density of PLT thin films were $580^{\circ}C$ 10mTorr, 10/1, and $1.7W/cm^{2}$, respectively. In these conditions, the c-axis growth and tetragonality of the PLT thin films decreased for addition of La content and the PLT thin films showed diffuse phase transition from high temperature XRD patterns. The infrared sensor was fabricated. The remanent polarization was above $1.71{\mu}C/cm^{2}$ and the pyroelectric voltage was above 500mV with 10:1 signal to noise ratio.

• Journal of Surface Science and Engineering
• /
• v.33 no.2
• /
• pp.77-86
• /
• 2000

In this study effects of La starting compounds and substrates on the densification of (P $b_{0.92}$L $a_{0.05}$)Ti $O_3$ thin films were investigated. After the heat treatment on platinized silicon at $650^{\circ}C$ for 30min thickness of PLT(i) thin films (from La-isopropoxide) shrank by 27%, while 33% reduction occurred for PLT (a) thin films (from La-acetate). These PLT(i) films showed less densified surface microstructure compared to the PLT (a) . Lower shrinkage of the films on platinized silicon than on bare silicon (41% and 40% for PLT (i) and PLT (a) respectively) is attributed to the earlier development of crystallinity in the film, which arrests film densification. In order to maximize sintering before crystallization, heat treatment at $400^{\circ}C$ for 3 hours followed by $650^{\circ}C$ for 30 min was attempted. This method increased the shrinkage of the PLT (i) and PLT (a) films two times and 1.5 times as much as that observed for the films heat treated at $650^{\circ}C$ for 30min, respectively. FTIR results indicated that first pyrolysis in the film is associated with the burning of acetate ligands. Condensation reaction between OHs was found to occur preferentially between $350^{\circ}C$ and $450^{\circ}C$, whereas majority of polycondensation between ROH-OH appears to occur until $300^{\circ}C$ and be completed below $450^{\circ}C$.EX>.

• Transactions on Electrical and Electronic Materials
• /
• v.1 no.1
• /
• pp.17-21
• /
• 2000

In order to investigate the dependence of a content in lead lanthanum titanate (PLT) films and heat treatment, sol-gel process has been used. Four types of PLT thin films with the chemical formula, Pb$\_$1-x/ La$\_$x/Ti$\_$1-x/4/O$_3$(X=18, 21, 24 and 28 mole %) have been fabricated on Pt/Ti/SiO$_2$/Si multi-layers and ITO/glass substrates, The post-annealing temperature in the range of 400~700 $\^{C}$ is applied for the formation of perovskite structure in PLT films. The structureal, electrical and optical properties of PLT film with the addition of La content are estimated. The films orientation and surface structure of films are studied by XRD (X-ray diffraction) and SEM(scanning electron microscopy). The P-E hysteresis loop become narrower with increasing La content. The average transmittance of the films is about 80%.