• Transactions on Electrical and Electronic Materials
• /
• v.13 no.4
• /
• pp.192-195
• /
• 2012

We reported diborane ($B_2H_6$) doped wide bandgap hydrogenated amorphous silicon oxide (p-type a-SiOx:H) films prepared by using silane ($SiH_4$) hydrogen ($H_2$) and nitrous oxide ($N_2O$) in a radio frequency (RF) plasma enhanced chemical vapor deposition (PECVD) system. We improved the $E_{opt}$ and conductivity of p-type a-SiOx:H films with various $N_2O$ and $B_2H_6$ ratios and applied those films in regards to the a-Si thin film solar cells. For the single layer p-type a-SiOx:H films, we achieved an optical band gap energy ($E_{opt}$) of 1.91 and 1.99 eV, electrical conductivity of approximately $10^{-7}$ S/cm and activation energy ($E_a$) of 0.57 to 0.52 eV with various $N_2O$ and $B_2H_6$ ratios. We applied those films for the a-Si thin film solar cell and the current-voltage characteristics are as given as: $V_{oc}$ = 853 and 842 mV, $J_{sc}$ = 13.87 and 15.13 $mA/cm^2$. FF = 0.645 and 0.656 and ${\eta}$ = 7.54 and 8.36% with $B_2H_6$ ratios of 0.5 and 1% respectively.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.11 no.4
• /
• pp.314-320
• /
• 1998

In this study, we have investigated crystallization properties of $Te_x(Sb_{85}Ge_{15})_{100-x}$ (x=0.3, 0.5, 1.0) thin films prepared by thermal evaporation. The change of reflectance according to phase change from amorphous to crystalline phases with annealing and exposure of diode laser is measured b the n&k analyzer and the surface morphology between amorphous and crystalline phase is analyzed by SEM and AFM. The difference in reflectance($\DeltaR$) between amorphous and crystalline phase appears approximately 20% at the diode laser wavelength, 780nm in all prepared films. Especially, the reflectance difference,$\DeltaR$ comes up to about 30% in $Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ thin film. Also, amorphous-to-crystalline phase change is observed in all prepared films. As a result of the measurement of the reflectance using diode laser, the reflectance is increased in proportion to the laser power and exposure time in all films. As a result of observing each film with the SEM and AFM, the surface morphology of the annealed and the exposed films are evidently increased than those of as-deposited films. The fast crystallization is occurred by increasing in Te content. Therefore, we conclude that the $Te_{0.5}(Sb_{85}Ge_{15})_{99.5}$ and $Te_1(Sb_{85}Ge_{15})_{99}$ thin films can be evaluated as an attractive optical recording medium with high contast ratio and fast erasing time due to crystallization.

• Journal of the Korean Magnetics Society
• /
• v.18 no.6
• /
• pp.227-231
• /
• 2008

Magnetic and structural properties of CoFeZr alloy films as a function of Zr concentration and magnetoresistive properties of spin valves incorporated with amorphous CoFeZr alloy films have been studied. Magnetization and coercivity of CoFeZr alloy films decreased as the Zr content increased. A single amorphous CoFeZr phase was formed when the Zr content is about above 18 at%. Magnetoresistance ratio and exchange coupling field of spin valves with amorphous CoFeZr were reduced slightly as compared with spin valves with CoFe because the resistance of amophous CoFeZr is higher than that of crystalline CoFe. However, the ${\Delta}{\rho}$ of spin valves with amorphous CoFeZr was improved due to reduction of current shunting.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.32 no.5
• /
• pp.376-381
• /
• 2019

In this work, we evaluated the structural, electrical and optical properties of $Ge_8Sb_2Te_{11}$ and Cu-doped $Ge_8Sb_2Te_{11}$ thin films prepared by rf-magnetron reactive sputtering. The 200-nm-thick deposited films were annealed in a range of $100{\sim}400^{\circ}C$ using a furnace in an $N_2$ atmosphere. The amorphous-to-crystalline phase changes of the thin films were investigated by X-ray diffraction (XRD), UV-Vis-IR spectrophotometry, a 4-point probe, and a source meter. A one-step phase transformation from amorphous to face-centered-cubic (fcc) and an increase of the crystallization temperature ($T_c$) was observed in the Cu-doped film, which indicates an enhanced thermal stability in the amorphous state. The difference in the optical energy band gap ($E_{op}$) between the amorphous and crystalline phases was relatively large, approximately 0.38~0.41 eV, which is beneficial for reducing the noise in the memory devices. The sheet resistance($R_s$) of the amorphous phase in the Cu-doped film was about 1.5 orders larger than that in undoped film. A large $R_s$ in the amorphous phase will reduce the programming current in the memory device. An increase of threshold voltage ($V_{th}$) was seen in the Cu-doped film, which implied a high thermal efficiency. This suggests that the Cu-doped $Ge_8Sb_2Te_{11}$ thin film is a good candidate for PRAM.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1993.11a
• /
• pp.64-66
• /
• 1993

The charateristics of low temperature poly-Si thin films with different growth condition were investigated and poly-Si TFTs were fabricated on solid phase crystallized (SPC) amorphous silicon films and as-deposited poly-Si films. The performance of devices fabricated on the SPC amorphous silicon films was shown to be superior to that of devices fabricated on as-deposited poly-Si films. It was found that the characteristics of low-temperature poly-Si thin films such as surface roughness, crystal texture and grain size strongly influenced the poly-Si TFT performance.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.12
• /
• pp.71-79
• /
• 1994

In this paper, $As_{40}Se_{50-x}S_[x}Ge_{10}$(x=0, 25, 35, at.%) bulk and thin films, to develope device of reversible hologram, proved amorphous by X-RD analysis. On the thin films with composition rate, as Se-doped-quantity increased, absorption edge shifted to long wavelength, and we found that reversible photodarkening effect occurred when thin films are exposed and annealed. Optical energy gap was larger when thin films are annealed than exposed. In this effect thin films structurally stabilized by annealing. It is to formed grating hologram by the bragg method on the $As_{40}Se_{15}S_[35}Ge_{10}$ thisn films with the best transmittance properties As polariging angle grew larger, we found that maximum diffraction efficiency became smaller, and obtained it of 4.5% on the thin fim thicknesss of 0.6 m, polarizing angle of 40$^[\circ}$ and exposing for 20sec.

• Journal of the Korean Ceramic Society
• /
• v.28 no.11
• /
• pp.859-864
• /
• 1991

High quality lead titanate thin films were fabricated by spin coating on a silicon substrate. The resulting dried gel layers were uniform in thickness through 2$\times$2 $\textrm{cm}^2$ area, and polycrystalline perovskite structures developed almost crack free with a heat treatment above 50$0^{\circ}C$ in films with thickness above 360 nm. Metastable pyrochlore structures were observed in films with thickness of 160 nm when heat treated at 500 and $600^{\circ}C$, but these structure did not appear in films with thickness of 360 nm. The thickness dependence in crystal structure of films was studied. by varying the substrate condition and analyzing the interface between the film and substrate. In native oxide films on silicon stbstrates, amorphous dried gel layers were heterogeneously nucleated. Metastable cubic pyrochlore structure could be crystallized in amorphous native oxide.

• Journal of the Korean institute of surface engineering
• /
• v.26 no.3
• /
• pp.127-134
• /
• 1993

P+ and BF2+ were implanted to LPCVD amorphous silicon films deposited on thermally-oxidized silicon wafers and the low temperature annealing process followed with various conditions to activate implanted ions and to recrystallize the films. We tried to find the optimum processing condition by comparing the recrystallization behaviors and the electrical properties. TEM analysis showed that the final grain size of BF2+-implanted films was similar to that of unimplanted films, whereas the grains of P+-implanted films. For both P+ - and BF2+ -implanted films, sheet resistances were decreased with elevating annealing temperature and the minimum value was about 110~120$\Omega$/$\square$ at $600^{\circ}C$.

• KIEE International Transactions on Electrophysics and Applications
• /
• v.12C no.4
• /
• pp.208-213
• /
• 2002

The present study describe the electrical performance of amorphous T $a_2$ $O_{5-X}$ fabricated on the buffer layers Ti and Ti $O_2$. T $a_2$ $O_{5-X}$ thin films were grown on the Ti and Ti $O_2$ layers as a capacitor layer using reactive sputtering method. The X-ray pattern analysis indicated that the two as-deposited films were amorphous and the amorphous state was kept stable on the RTA(rapid thermal annealing) at even $700^{\circ}C$. Measurements of dielectric properties of the reactive sputtered T $a_2$ $O_{5-X}$ thin films fabricated in two simple MIS(metal insulator semiconductor), structures, (Cu/T $a_2$ $O_{5}$ Ti/Si and CuT $a_2$ $O_{5}$ Ti $O_2$Si) show that the amorphous T $a_2$ $O_{5}$ grown on Ti showed high dielectric constant (23～39) and high leakage current density(10$^{-3}$ ～10$^{-4}$ (A/$\textrm{cm}^2$)), whereas relatively low dielectric constant (～15) and tow leakage current density(10$^{-9}$ ～10$^{-10}$ (A/$\textrm{cm}^2$)) were observed in the amorphous T $a_2$ $O_{5}$ deposited on the Ti $O_2$ layer. The electrical behaviors of the T $a_2$ $O^{5}$ thin films were attributed to the contribution of Ti- $O_2$ and the compositionally gradient Ta-Ti-0, being the low dielectric layer and high leakage current barrier. In additional, The T $a_2$ $O_{5}$ Ti $O_2$ thin films exhibited dominant conduction mechanism contributed by the Poole-Frenkel emission at high electric field. In the case of T $a_2$ $O_{5}$ Ti $O_2$ thin films were related to the diffusion of Ta, Ti and O, followed by the creation of vacancies, in the rapid thermal treated thin films.films.

• Electrical & Electronic Materials
• /
• v.9 no.7
• /
• pp.690-695
• /
• 1996

We have systematically investigated the characterization of V$_{2}$O$_{5}$ thin films as a counter electrode for lithium based complementary electrochromic devices. The V$_{2}$O$_{5}$ thin films were prepared by thermal vacuum evaporation with varing the substrate temperature and film thickness. In electrochromic devices for smart windows, the WO$_{3}$ thin films with 400-800 nm thickness require to be capable of reversibly injection 10-15 mC/cm$^{2}$ of lithium, which is readily accomplished charge-balanced switching in a V$_{2}$O$_{5}$ thin films with 100-150nm thick. The V$_{2}$O$_{5}$ thin films produces considerably small changes in optical modulation properties in the visible and near infrared region(500-1100 nm) compared to the amorphous WO$_{3}$ thin films on 10-15 mC/cm$^{2}$ of lithium injection and the V$_{2}$O$_{5}$ thin films can therefore act as a counter electrode to WO$_{3}$ in a lithium based complementary clectrochromic devices. After 10$^{5}$ coloration/bleaching switching time, the degradation does not occurs and the devices exhibit a stable optical modulation in V$_{2}$O$_{5}$ thin films. It has shown that the injected lithium ion amounts in crystalline V$_{2}$O$_{5}$ thin films with the same thickness is large by 3-5 mC/cm$^{2}$ of lithium compared to the amorphous thin films in the same driving conditions. Therefore, to optimize the device performance, it is necessary to choose an appropriate film thickness and crystallinity of V$_{2}$O$_{5}$ for amorphous WO$_{3}$ film thickness as a working electrode.