Dip‐Coating of Sb‐Doped SnO2 Films by Ethanolamine‐Alkoxide Method

Abstract

Transparent, highly conducting thin Sb-doped SnO= films have been deposited on glass by a dip-coating method using a solution of tin tetraisopropoxide-triethanolamine-H20-isopropanol. The viscosity of the solution obtained from this system remained constant over 700h. The resistivity of the film depended slightly on film thickness: it was 0.025 ~ -cm below 1000A and decreased to a constant value of 0.005 ~ -cm above 2000A. Average transmittance of visible light was higher than 95% for undoped films and higher than 80% for Sb-doped films. The coated thin films were very uniform and dense, whereas an OMCVD process formed porous films with an island texture. The advantages and disadvantages of the dipcoating process are discussed in comparison with the OMCVD process.SnO2 films are used as transparent electrical conductors and in gas-sensing devices. Highly conductive films have been prepared by chemical vapor deposition (CVD) (1-12) including organometallic CVD (OMCVD) (13-27), sputtering (28-31), ion plating (32), spraying methods, thermal evaporation (33), and the dip-coating process (34,35). The last method is of interest because it has a great advantage of easily coating large substrates. The systems, tin alkoxide-HCl-alcohol (34) and tin carboxylates-alcohol (35), have been proposed for the dip-coating of the SnO2 films. However, the former system is unstable that it is difficult to keep the viscosity of the solution constant for long periods of time and hence to control the film thickness reproducibly. The latter system contains less soluble species such as carboxylates and tends to produce less uniform films with somewhat higher resistivities.In our previous paper on the dip-coating of doped zirconia (36), spinel (37), and titania films (38), we reported that glycols or ethanolamines are especially useful to control the hydrolysis rate of the metal alkoxides, and can yield very suitable solutions for dip-coatings of the oxides. Diethanolamine and related chemicals can be used as inhibitors for the precipitation of oxides on hydrolysis of the alkoxides. Expecting similar effects of ethanolamines on tin alkoxide, we examined the tin alkoxide-ethanolamines-H20-isopropanol system. We report here the results of this study, in which we found that the systein is very useful for the dip-coating o.f uniform, transparent SnO2 films. We have previously investigated OMCVD of SnO2 films using n-butyltin as a source (39), permitting comparisons to be made of the qualities of the films prepared by the dip-coating and those deposited by OMCVD. ExperimentalCommercial Sn(O-i-Pr)4 (2N purity, High Purity Chemicals Company Limited), extra pure grade triethanolamine (TEA), and isopropanol were used without further purification.To an isopropanol solution of the alkoxide (0.1-0.7M) one molar equivalent TEA was added at room temperature, and the mixture was stirred at room temperature for 2h. Then a given amount of deionized water diluted with isopropanol was added drop-wise to the solution and the mixture was stirred at ro...

Precursors for the Formation of Tin(IV) Oxide and Related Materials

“…15 These data are also very similar to Sb:SnO 2 produced by dip coating [Sn(OPr i ) 4 /Sb(OEt) 3 /triethanolamine/H 2 O/ i PrOH ]. 42 Tin alkoxides, b-diketonates and carboxylates comprise the classes of metal-organic precursor used to deposit SnO 2 . Both Sn(II) and Sn(IV) alkoxides have been exploited, though the lower oxidation state gives rise to hybrid materials incorporating both Sn 0 and tin oxides, and are discussed later in this review.…”

Fabrication and characterization of Sb-doped Sn0 2 thin films derived from methacrylic acid modified tin(IV)alkoxides

“…The relatively low conductivity values, compared to other reports concerning the sol-gel derived Sb-doped tin dioxides, 13,18 can be attributed to the morphology of single layer coatings. 1,14,19 In the next part of this paper the reasons for increased conductivities of the UV-irradiated samples are analyzed.…”

Photoluminescent studies on porous silicon/tin oxide heterostructures

“…To take benefit from the intense red photoluminescence (PL) of PSi at room temperature [1], many attempts have been made to introduce PSi in the circuitry of some silicon-based optoelectronic devices. Indium tin oxide (ITO) or semitransparent Au electrodes were frequently used as transparent conducting electrodes in PSi-based LED structures [2,3]. These electrodes can be deposited by various methods such as chemical vapor deposition, sputtering or thermal evaporation.…”