別紙4 (課程博士)
Date of submission

平成29年

1月12日

StudentlD Number

Depanment

機械工学専攻Pplicarlt's name

氏名

学籍番号

第 103242 号

Supervisors

伊崎昌伸

指導教員

西山健太朗
Abstract

論文内容の要旨(博士)Study on Electrochemicalpreparation ofoxide semiconductor Films

Title ofThesis

博士学位論文名(酸化物半導体膜の電気化学形成に関する研究)(Approx.80o words)
き''叉(要旨 1,200字程度)
Metal oxide films have been utilized in electronics and chemicalindustries due totheir electrical, optical, piezoelectrical, and ma晉netic characteristics. The oxides
have been also used as host materials for transparent conductive layers, electronic

Parts such as thin 丘lm transistors and capacitors and photocatalysts. Especia11y,
Oxide semiconductor layers with wide band今ap ener牙y over 2 ev have attracted
in仇,easin晉 attention as materials to open new door for ultraviolet H牙ht、emittin牙 diode(LED), spintronics, and multi ferroic materials with contr011ed physicalCharacteristics.

Oxide semiconductor films have been prepared usin牙牙as"phase deposition processes

イ︑︑and solution chemical processes. Gas'phase deposition processes have severaladvantages Hke the ability to controlthickness and form hi今h purity semiconductors,
With disadvantages of expensive apparatus, the need of facility for 今asses and hi今hVacuum, resultin今 in lar今e amount of ener部 Consumption and c02 emission.
Solution chemical processes have several advanta今es over the 今as"phase deposition
Processes in the equipment, facilities, and fabrication costs, and electrochemical

Processes have been employed to prepare precursors of cu(1n,Ga)se2 (CIGS) andCU2ZnsnS4(CZTS) compounds for photovoltaic applications on the industry scale.
The wide bandgap oxide semiconductor films were applied to optical devices, and it
is weⅡ known that their compositions, structures and chemicalstates inauence their
Optical properties. However, electrochemical preparation for oxide semiconductor
films applied to optical devices has some problems.1t is we11 known that m.ixing
Other materials to an oxide semiconductor chan牙es its opticalproperties and electrical

Properties, but almost no example of a mixed、oxide film is reported. Moreover,
Valence values ofmetalelements in oxide were uncontr011able because ofthe existence

Of mixes valence elements and impurities, and this led to the uncontr011ability of
Optical properties and electrical properties of oxide semiconductor. These problems
Can be solved by desi牙nin牙 the processes with thermodynalnic calculation.1n thisthesis,1 Show' resolving these problems using electrochemical preparation of oxide

丘lms based on thermodynamic calculation with some examples, and l demonstrate anovel device fabricated by electrochemical preparation overcomin牙 Weaknesses ofexisting device, in order to show' the possibility for industrial applicationsFirst, zn、ce、o films, mixed oxide films, were prepared on an electrodeposited Ag
Iayer in an aqueous solution containing a zinc nitrate hydrate and cerium nitrate
hydrate based on thermodynamic calculation. Theory of deposition for mixed"oxide
丘lms was discussed from a critical pH pe玲Pective relative to ion species and oxides
The concentrations of metalions in the zn"ce"o films were depending on ionsConcentration ofzn and ce in the solution. The ce contentin the films chan牙ed fromO t043 m01% dependin号 on the ce concentration in solutions. zn、ce、o films wereidentified as a w'urtzite zno containing ce (ce:zno) at 5 m01% ce and mixtures ofCe:zno and ce02 Containing zn(zn:ce02) at 20‑43 m01% ce. The band今ap ener今y ofZn・ce・o films have changed from 3.4 ev t02.9 ev depending on the ce content.
Secondly,1 demonstrated preparation of tungsten oxide hydrate films of w03'H20
and X入703くH20)0.33 With a contr011ed valence value of the metal element in the oxides/Usin号 electrochemicalpreparation based on thermodynamic calculation. The valenceState ofobtained tungsten oxide hydrate films was only +6, and this film w'as proved tohave hi今h chemical uniformity Tun牙Sten oxide hydrate 6.1ms of X入703'H20 and＼入7'03くH20)033 W'ere prepared on conductive glass substrates by anodic deposition inaqueous solutions containin曾 0.01‑0.5 movL W042‑. The lar今e square、shaped
X入703・H20 obtained in the o.01‑0.09 movLW042‑solutions possessed abandgap ener今yOf approximately 2.5 eY and granular・＼入103くH20)0.器{ilms obtained in the o.05‑0.5
movL X入7042‑ solutions showed 3.3 ev in band今ap ener牙y
Thirdly, on the basis of thermodynamic calculations,1 tried to form sn02 films

having uniformity in valence. sn(0,OH), mixture of sn02 and sn(OH)4, having
W'as

Prepared by electrodeposition desi套ned using

thermodynamic calculations. obtained sn(0,OH) completely covered the substrates,
and had smooth surfaces and structures with tetragonalfine crystals

Fina11y,1 fabricated the X入703くH20)0.33/sn(0,OH) bilayer structure for a11・solid'stateelectrochromic device by anodic electrodeposition on the FTo substrate. The

X入103くH20)0.33/sn(0,OH) bilayer device showed electrochromisln; this was an evident
demonstration ofa novel and low"costly a11、solid、state electrochromic device
I resolved the problems of existin今 electrodeposition for w'ide band 今ap oxide
Semiconductor by electrochemical preparation based on thermodynamic calculation
The results demonstrated here wiⅡ Stron今ly contribute to the improvement of thePreparation process ofoxide semiconductors and their devices

ii

Unified valence of +4ノ