Indium tin oxide (ITO) is a well-known metal oxide degenerate semiconductor. It is a wide band gap (∼ 3.5eV), n-type oxide semiconductor which has a low resistivity (in the order of 10^-^0 Ω㎝) and high transmittance (∼ 90%) in the visible range. In general, IO(Indium oxide), TO(Tin oxide), ATO(Antim...
Indium tin oxide (ITO) is a well-known metal oxide degenerate semiconductor. It is a wide band gap (∼ 3.5eV), n-type oxide semiconductor which has a low resistivity (in the order of 10^-^0 Ω㎝) and high transmittance (∼ 90%) in the visible range. In general, IO(Indium oxide), TO(Tin oxide), ATO(Antimony doped Tin oxide), ZO(Zinc oxide), IZO(Indium doped Zinc oxide), CTO(Cadmium Stannate) and FITO(Fluorinated Indium Tin oxide) have been widely studied as the possibel candidates for transparent conductive oxides (TCO). Among them, ITO films are known to decrease resistivity significantly because substitutional tin dopants into oxygen vacancies create a high carrier concentration caused by the overlap of the Fermi level with the conduction level at the bottom of the conduction band : therefore, ITO films have been widely used as LCD, ELD, FED, solar cell, photovoltaic cell, biological devices and storage-type cathode ray tube. For the growth of ITO thin films on various substrates many techniques have been utilized such as MOCVD, PECVD, Reactive electron beam evaporation, Evaporation, DC and RF Sputtering, Spray pyrolysis, RTE, DC magnetron Sputtering, RF magnetron Sputtering and sol-gel methods. In this study, ITO thin films were deposited by r.f. reactive magnetron sputtering system(13.56 MHz). The target was an indium tin (90:10) alloy with a purity of 99.999%(2×1/4 inch). The substrate was PET(polyethylene terephthalate) and the distance between the target and substrate was about 10cm. The vacuum chamber was evacuated to a pressure of 6.4 ×10^-4 Torr piror to four different conditions of deposition After that, Argon and oxygen gases were introduced the condition of deposition, the target was presputtered(10 min) in an argon gas in order to remove the surface oxide layer and the contaminant on the surface of target. The sheet resistance was measured by four point probe and the resistivity, carrier concentration and carrier mobility were measured by Hall effect. The film thickness was measured by Alpha step and the surface structure of film was examined by SEM. The composition of film was measured by EDX. As results, the resistivity decreased with the increase of oxygen flow rate ratio up to 8%(6.9 × 10^-3 Ωcm) and the further oxygen flow rate ratio increased the resistivity. The transmittance was tended to increase as the oxygen flow rate ratio increased. The transmittance in oxygen flow rate ratio of 10% was 85%. The best carrier concentration was □ 5.9×10^19cm ^-3 and the carrier mobility was □37.62 ㎠/V*sec). The grain size turned out to decrease as the oxygen flow rate ratio increased and little increased at 12%. In various RF powers, the resistivity was described resistivity well and the transmittance was 85% at 40 and 50 W. However, the transmittance was measured to be 30% at 60 W. The surface morphology became gradually rough with increasing RF power. In various pressures, the resistivity was decreased with the increase of working pressure at 50 W and oxygen flow rate ratio 10%. The resistivity was 5.6×10^-3 Ωcm at 4.2×10 mTorr and the transmittance was 85%. The grain size was increased with increase working pressure and morphology was rough. The effect of working time(thickness) was observed that the resistivity was decreased with increase working time up to 39min(2700Å, 1.6 ×10^-3 Ωcm ) and further working time increased resistivity. The transmittance was gradually increased.
Indium tin oxide (ITO) is a well-known metal oxide degenerate semiconductor. It is a wide band gap (∼ 3.5eV), n-type oxide semiconductor which has a low resistivity (in the order of 10^-^0 Ω㎝) and high transmittance (∼ 90%) in the visible range. In general, IO(Indium oxide), TO(Tin oxide), ATO(Antimony doped Tin oxide), ZO(Zinc oxide), IZO(Indium doped Zinc oxide), CTO(Cadmium Stannate) and FITO(Fluorinated Indium Tin oxide) have been widely studied as the possibel candidates for transparent conductive oxides (TCO). Among them, ITO films are known to decrease resistivity significantly because substitutional tin dopants into oxygen vacancies create a high carrier concentration caused by the overlap of the Fermi level with the conduction level at the bottom of the conduction band : therefore, ITO films have been widely used as LCD, ELD, FED, solar cell, photovoltaic cell, biological devices and storage-type cathode ray tube. For the growth of ITO thin films on various substrates many techniques have been utilized such as MOCVD, PECVD, Reactive electron beam evaporation, Evaporation, DC and RF Sputtering, Spray pyrolysis, RTE, DC magnetron Sputtering, RF magnetron Sputtering and sol-gel methods. In this study, ITO thin films were deposited by r.f. reactive magnetron sputtering system(13.56 MHz). The target was an indium tin (90:10) alloy with a purity of 99.999%(2×1/4 inch). The substrate was PET(polyethylene terephthalate) and the distance between the target and substrate was about 10cm. The vacuum chamber was evacuated to a pressure of 6.4 ×10^-4 Torr piror to four different conditions of deposition After that, Argon and oxygen gases were introduced the condition of deposition, the target was presputtered(10 min) in an argon gas in order to remove the surface oxide layer and the contaminant on the surface of target. The sheet resistance was measured by four point probe and the resistivity, carrier concentration and carrier mobility were measured by Hall effect. The film thickness was measured by Alpha step and the surface structure of film was examined by SEM. The composition of film was measured by EDX. As results, the resistivity decreased with the increase of oxygen flow rate ratio up to 8%(6.9 × 10^-3 Ωcm) and the further oxygen flow rate ratio increased the resistivity. The transmittance was tended to increase as the oxygen flow rate ratio increased. The transmittance in oxygen flow rate ratio of 10% was 85%. The best carrier concentration was □ 5.9×10^19cm ^-3 and the carrier mobility was □37.62 ㎠/V*sec). The grain size turned out to decrease as the oxygen flow rate ratio increased and little increased at 12%. In various RF powers, the resistivity was described resistivity well and the transmittance was 85% at 40 and 50 W. However, the transmittance was measured to be 30% at 60 W. The surface morphology became gradually rough with increasing RF power. In various pressures, the resistivity was decreased with the increase of working pressure at 50 W and oxygen flow rate ratio 10%. The resistivity was 5.6×10^-3 Ωcm at 4.2×10 mTorr and the transmittance was 85%. The grain size was increased with increase working pressure and morphology was rough. The effect of working time(thickness) was observed that the resistivity was decreased with increase working time up to 39min(2700Å, 1.6 ×10^-3 Ωcm ) and further working time increased resistivity. The transmittance was gradually increased.
Keyword
#R. F. 마그네트론 스퍼터링법 ITO/PET박막
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