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Title:	Physical properties of indium oxide thin films doped and co-doped with transition metals (Fe, Cr, Co and Cu)
Authors:	Hussein Abdullah Hussein Baqiah (P55910)
Supervisor:	Noor Baayah Ibrahim, Assoc. Prof. Dr
Keywords:	Transition metals doped Co-doped Single doped Universiti Kebangsaan Malaysia -- Dissertations Dissertations, Academic -- Malaysia
Issue Date:	8-Apr-2014
Description:	Transition metals doped wide band gap semiconductors that combine between transparency, semiconducting and magnetic behavior open a possibility for new spintronic devices besides their applications in electronic and sensor devices. In this study, indium oxide doped with transition metals (In2-xMxO3; M=Fe, Cr or Co) noted as single doped set and indium oxide co-doped with transition metals (In1.95-yCr0.05M'yO3 or In1.9-yCo0.1M'yO3: M'=Fe or Cu) noted as co-doped set, were prepared by a sol-gel method followed by a spin coating technique. Films that show the best magnetic and electrical properties from the single and co-doped sets (In1.975Fe0.025O3 and In1.925Cr0.05Cu0.025O3) were annealed in hydrogen at 300, 400, 500 and 600°C and noted as hydrogen set. The X-ray diffraction results indicated that the single doping and codoped sets had single phase structures. The lattice parameter decreased with single or co-doping indicating that the transition metal ions had been incorporated into the indium oxide matrix. The In1.975Fe0.025O3 film annealed in hydrogen at 300-500°C had single phase while it had mixed phase structure when annealed at 600°C. The In1.925Cr0.05Cu0.025O3 thin films annealed in hydrogen had an amorphous like structure when annealed at 300°C and single phase at 400°C while mixed phases were observed when annealed at 500-600°C. The grain size of single doped sets measured using transmission electron microscopy was ~10nm. The grain size of Cr or Co doped In2O3 films decreased with the increment of dopant, while their band gap increased as grain size decreased. The grains sizes of In1.95-yCr0.05M'yO3 or In1.9-yCo0.1M'yO3 decreased with Cu or Fe co-doped and were less than 7 nm while their band gap increased with decrease of grain size. For the hydrogen sets, the grain size increased with increased annealing temperature while the band gap decreased. The Hall Effect measurements showed that In2-xFexO3(x=0.0-0.05) and In2-xCrxO3(x=0.0-0.075) films had semiconductor behavior. However, the Co single doped set and In1.9-yCo0.1M'yO3 exhibited insulating behavior. All conducting films had n-type conductivity except for In1.925Cr0.05Cu0.025O3 annealed in air, which had p-type conductivity. The resistivity of In1.975Fe0.025O3 thin films annealed in hydrogen at 300-500°C have the lowest value among the single or co-doped sets and it had insulator like behavior when annealed at 600°C. The conducting mechanisms of conducting films at a low temperature were explained using thermally activated conduction band and hopping models. The magnetization of a single dopant set depended on the type of magnetic ions and its dopant concentrations. For Fe single doped set the highest saturation magnetization, Ms value (21emu/cm3 ) was given by the film, x=0.025, while for Cr and Co single doped sets with their highest Ms, are 9 and 26 emu/cm3 , were given by films with x=0.15 and 0.1, respectively. The co-doped set exhibited weaker Ms or (paramagnetic behavior) than that of single doped. The highest Ms (6 emu/cm3 ) of co-doped sets was observed with Cu co-doped. The Ms of In1.975Fe0.025O3 increased with the increment of annealing temperature in hydrogen up to 600°C. The Ms of In1.925Cr0.05Cu0.025O3 increased with increasing of annealing temperature in hydrogen up to 500°C. The magnetic behavior of films was explained by a bound magnetic polaron model (BMP). Single doped sets of Fex=0.025 or Crx=0.05 and In1.975Fe0.025O3 thin film annealed at 500°C in hydrogen are good candidates for spintronic applications. The Cr single doped In2O3 thin film with x=0.075, that has porous like nanostructure will be a good candidate for gas sensor. The In1.975Fe0.025O3 thin film annealed in hydrogen at 300°C is a good candidate as an electrode on substrate. The In1.925Cr0.05Cu0.025O3 thin film is a good candidate for p-type conductors application.,Semikonduktor berjurang lebar terdop logam peralihan yang menggabungkan antara sifat lutsinar, semikonduktor dan magnet membuka kebarangkalian kepada peranti spintronik yang baru, diamping kegunaan mereka di dalam peranti sensor dan elektronik. Dalam kajian ini, indium oksida terdop logam peralihan (In2-xMxO3; M=Fe, Cr or Co) dinamakan set dop tunggal dan indium oksida ko-dop dengan logam peralihan (In1.95-yCr0.05M'yO3 or In1.9-yCo0.1M'yO3: M'=Fe or Cu) dinamakan sebagai set ko-dop, disediakan dengan kaedah sol-gel diikuti dengan teknik salutan berputar. Filem yang menunjukkan sifat magnet dan elektrik yang terbaik disepuhlindap dalam hidrogen pada 300, 400, 500 dan 600°C dan dinamakan sebagai set hidrogen. Hasil kajian belauan sinar-X menunjukkan set dop tunggal dan ko-dop mempunyai fasa tunggal. Parameter kekisi berkurangan dengan pendopan tunggal dan ko-dop menunjukkan ion logam peralihan telah memasuki matriks indium oksida. Filem In1.975Fe0.025O3 yang disepuhlindap pada 300-500°C mempunyai fasa tunggal sementara ianya mempunyai fasa bercampur apabila disepuhlindap pada 600°C. Filem In1.925Cr0.05Cu0.025O3 yang disepuhlindap dalam hidrogen pada 300°C mempunyai struktur amorfus dan fasa tunggal pada 400°C sementara fasa bercampur dapat dilihat apabila disepuhlindap pada 500-600°C. Saiz butiran set dop tunggal yang diukur dengan mikroskop transmisi elektron adalah ~ 10nm. Saiz butiran bagi Cr atau Co terdoped In2O3 berkurangan dengan penambahan dopan, sementara jurang jalurnya bertambah apabila saiz butiran berkurangan. Saiz butiran In1.95-yCr0.05M'yO3 atau In1.9-yCo0.1M'yO3 berkurangan dengan ko-dop Cu atau Fe adalah kurang dari 7nm sementara jurang jalur bertambah dengan pengurangan saiz butiran. Bagi set hidrogen, saiz butiran bertambah dengan penambahan suhu sepuhlindap sementara jurang jalur berkurangan. Pengukuran kesan Hall menunjukkan bahawa filem In2-xFexO3(x=0.0-0.05) dan In2-xCrxO3 (x=0.0-0.075) bersifat semikonduktor. Namun begitu, set dop tunggal Co dan In1.9-yCo0.1M'yO3 menunjukkan sifat penebat. Kesemua filem konduktor mempunyai kekonduksian jenisn kecuali In1.925Cr0.05Cu0.025O3 yang disepuhlindap dalam udara biasa mempunyai kekonduksian jenis-p. Kerintangan filem In1.975Fe0.025O3 yang disepuhlindap dalam hidrogen pada suhu 300-500°C mempunyai kerintangan yang lebih rendah dari set dop tunggal atau ko-dop dan mempunyai sifat seperti penebat apabila disepuhlindap pada suhu 600°C. Mekanisma pengkonduksi bagi filem pengkonduksi pada suhu rendah dijelaskan melalui model lompatan dan model jalur konduksi diaktifkan terma. Pemagnetan set dop tunggal bergantung kepada jenis ion magnetik dan kepekatan dopan. Untuk set dop tunggal Fe, pemagnetan tepu, Ms yang terbesar (21emu/cm3 ) diberikan oleh filem x=0.025, sementara untuk Cr dan Co set dop tunggal dengan Ms terbesar adalah 9 dan 27emu/cm3 diberikan oleh filem x=0.15 and 0.1, masing-masing. Set ko-dop menunjukkan Ms yang kecil atau sifat paramagnet berbanding dengan dop tunggal. Ms yang terbesar (6 emu/cm3 ) dalam set ko-dop diberikan oleh ko-dop Cu. Ms bagi In1.975Fe0.025O3 meningkat dengan peningkatan suhu sepuhlindap di dalam hidrogen sehingga 600°C. Ms bagi In1.925Cr0.05Cu0.025O3 meningkat dengan set peningkatan suhu sepuhlindap di dalam hidrogen sehingga 500°C. Sifat magnetik filem dijelaskan dengan model polaron magnetik (BMP). Set dop tunggal Fe (x=0.025) atau Cr (x=0.05) dan In1.975Fe0.025O3 yang disepuhlindap pada 500°C merupakan calon yang sesuai untuk kegunaan spintronik. Filem Cr dop tunggal In2O3 dengan x=0.075 yang mempunyai struktur nano yang berliang adalah calon yang sesuai untuk sensor gas. Filem In1.975Fe0.025O3 yang disepuhlindap pada 300°C adalah calon yang bagus sebagai elektrod di atas substrak. Filem In1.925Cr0.05Cu0.025O3 adalah calon yang bagus untuk kegunaan konduktor jenis-p.
Call Number:	QD172.T6 B346 2014 tesis
Publisher:	UKM, Bangi
Appears in Collections:	Faculty of Science and Technology / Fakulti Sains dan Teknologi

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