Preparation and properties of oriented tin oxide thin films on glass substrates by spray pyrolysis of organotin compounds

Abstract

SnO2 thin films have been grown on glass substrates by the spray pyrolysis technique using a series of organotin compounds with butyl and/or acetate group: (C4H9)4Sn (TBT), (C4H9)3SnOOCCH3 (TBTA), and (C4H9)2Sn(OOCCH3)2 (DBTDA). The spray pyrolysis of TBT and DBTDA led to the deposition of the (110) and (200) oriented SnO2 thin films, respectively. On the other hand, any outstanding preferred orientation was not found in the film deposited from TBTA; i.e., the growth of (110), (200) or (211) plane was enhanced variously depending on film growth rate and substrate temperature. The oriented growth of these thin films occurs via the following three stages: (a) formation of SnO2 nuclei; (b) crystal growth of SnO2 with preferred orientations; and (c) further crystal growth normal to the surface of a substrate. The butyl and acetate groups of the source compounds facilitated the (110) and (200) oriented growths of SnO2 thin films, respectively. The electrical and optical properties of these thin films are also described.

ブチルまたはアセテート基を有する一連の有機すず化合物(C4H9)4Sn[TBT]、 (C4H9)3SnOOCCH3[TBTA]、および(C4H9)2Sn(OOCCH3)2[DBTDA]を用いたスプレー熱分解により、ガラス基板上にSnO2の薄膜を成長させた。TBTとDBTDAのスプレー熱分解により、それぞれ(100)と(200)配向のSnO2薄膜を蒸着した。他方、TBTAから蒸着した膜には、なんら顕著な優先配向はみられなかった。すなわち、(110)、(200)、または(211)面の成長は、膜成長速度と基板温度に依存して様々に増大した。これらの薄膜の配向成長は、次の3段階をへて生じる。(1)SnO2核の形成、(2)優先配向したSnO2結晶成長、さらに(3)基板表面に垂直な結晶成長。原料化合物のブチルおよびアセテート基は、それぞれSnO2薄膜の(110)と(220)配向の成長を容易にする。これらの薄膜の電気的および光学的性質についても述べた。