氏名・（本籍）
学位の種類 学位記番号 学位授与の日付 学位授与の要件
学位論文題・目
論文審査委員
Md．Akram Hossain（バングラデシュ）
工 学 博 士
工博甲第 40 号 昭和63年4月20日 学位規則第5条第1項該当
電子科学研究科 電子材料科学専攻
Electrochromic characterstics of sputtered tungstic oxide fiIms
（酸化タングステンスバッタ膜のエレクトロクロミック特性）
（委員長）
教 授 藤 安 洋
教 授 山 田 祥 二 教 授 熊 川 征 司
助教授 山 口十六夫 助教授 伊ケ 崎泰宏
論 文 内 容 の 要 旨
Tungstic oxide films are prepared from compressed powder WO3targetand W metal
target by rf sputterlng method・The optlmum preparation condition to obtain high efficiency for electrochromic（EC）colorationisinvestigated・It has been thought
that the sputtered films have poorer electrochromic properties than that of typlCal evaporated films・In thisinvestlgation・attemptS have been made to prove thatif the PrOper Sputtering parameter can be selected・itis possible to get coloration efficiency Of the sputtered films more than that of the typlCalevaporated films・Like evaporaIed films・Substrate temperature also affect coloration characterstics of the sputtered films．
if the substrate temperatureis equal or higher thanlO0℃，the col。ration。f the film becomes non uniform・If the substrate temperatureisless thanlO0℃，the coloration of
the filmis excellant・The substrate temperaturecan be controlled by thelnput rf power and water cooling of the substrate holder・Itis found that as−deposited sputtered films requlre aglng prOCeSS tO get the reversible coloration and bleaching characterstics．It is believed thatin theas−deposited film theremay besome unstable oxygen whose bonds
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are saturated by theintroduction of hydrogen atom durlng the aglng prOCeSS．Adsorbed H20is then produced．Therefore，hydrogenintroduced during aging（passive hydrogen）
is believed to be presentin the state of H20 adsorbedin the film．This passive hydrogen denslty dependslinearly on the film thickness．Passive hydrogen denslty increases withincreaslng the O2COntentS Of the sputterlng gaS．
Itis also fodnd that the as−deposited films are coloredif the total pressure and O2 COntentS Of the mixed gas are toolow．This as−deposited colored film ean be colored
more deeply by the simultaneousintroduction of protons and electrons，but can not be bleached upto the transparent state electrochemica11y．
Itis found that，after the aglng period，the change of optlCal denslty △ODis proportiopal to theinjected charge Q．Thelinearity of the △OD versus Q curves，
allowed us to define the coloration efficiency で aS the slope of the straightlinei．e．，
り＝△OD／Q．The maximum coloration efficiency obtained by this methodis O．06cm2／mC at the wavelength of600nm．This maximum coloration efficiencyis equal for both the targets．This valueis greter than that of typlCalevaporated film．
Preparation condition for maximum coloration efficiencylS
For W metaltarget：
Totalpressure：0．07−0．09Torr
O2 COntentS：＞15％
Input rf power：＜100W（1．3W／cm2）
For WO3target：
Totalpressure：0．04−0．05Torr
O2 COntentS：5％
Input rf power：50W（0．65W／cm2）
In case of WO3 targetitis found thatif theinput powerislOOW（1．3W／cm2）the Substrate temperatureis equal or higher thanlO0℃，SO the coloration of the films becomesnon uniform．Moreover，itis reported thatif the WO3targetis sputtered with
low oxygen content the surface of the target changes，i．e．，it become WO‥卜、．Butin
CaSe Of W metal target the substrate temperatureisless thanlOO℃for the．samelnf）ut power・Therefore to get the required thickness of the filmin a short period of time，W
metal targetis suitable・Itis also found thatif the films are preparedin the
atmosphere with high 02 COntent，paSSive part of hydrogenincreases and requlreSlong
aglng time・Considering the above polntSin mind，the optlmum Preparation condition of the films are as follows：
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Target：W metal
Totalpressure：0．07−0．09Torr
O2 COntent：15−20％
Input rf power：＜100W
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