Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12, BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen, air and oxygen atmos...Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12, BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen, air and oxygen atmospheres, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure, the surface and cross-section morphology of the deposited ferroelectric films. The results show that the crystallization atmosphere has significant effect on determining the crystallization and ferroelectric properties of the BDT films. The film crystallized in nitrogen at a relatively low temperature of 650 ℃, exhibits excellent crystallinity and ferroelectricity with a remanent polarization of 2Pr = 24.9 μC/cm2 and a coercive field of 144.5 kV/cm. While the films annealed in air and oxygen at 650 ℃ do not show good crystallinity and ferroelectricity until they are annealed at 700 ℃. The structure evolution and ferroelectric properties of BDT thin films annealed under different temperatures (600?750 ℃) were also investigated. The crystallinity of the BDT films is improved and the average grain size increases when the annealing temperature increases from 600 ℃ to 750 ℃ at an interval of 50 ℃. However, the polarization of the films is not monotonous function of the annealing temperature.展开更多
The possibility of ultra-thin Y2O3 (yttrium sesquioxide) films as insulator of metal ferroelectric insulator semiconductor (MFIS) structure was investigated. The ultra-thin Y2O3 films with thickness of 10-40 nm were f...The possibility of ultra-thin Y2O3 (yttrium sesquioxide) films as insulator of metal ferroelectric insulator semiconductor (MFIS) structure was investigated. The ultra-thin Y2O3 films with thickness of 10-40 nm were fabricated on p-type Si (100) substrates by molecular beam epitaxy(MBE) in vacuum and subsequently submitted to rapid thermal processing (RTP) in air ambient at 700, 800 and 900 ℃ for 30 min, respectively. The films were characterized by X-ray diffractometry and Raman spectroscopy. High frequency capacitance—voltage (C—V) characteristics and current—voltage (I—V) characteristics of the Y2O3/Si structure were analyzed. A Raman peak of the Y2O3 thin films was observed at 378 cm-1. From the C—V data, these films exhibit dielectric constants ranging from 13 to 17.28, the hysteresis width (△VFB) ranging from 0.07 to 0.22 V and the density of trapped charges ranging from 1.65×1011 to 4.01×1011 cm-2. A leakage current of 4.75×10-8 -9.0×10-6 A/cm2 at 1.5 MV/cm was observed. The results show that the Y2O3 buffer layers are suitable for non-volatile MFIS structure field-effect-transistors (FETs) memory application.展开更多
基金Project (05FJ2005) supported by the Key Project of Scientific and Technological Department of Hunan Province, China Project (05C095) supported by the Research Funds of Educational Department of Hunan Province, China
文摘Dysprosium-doped Bi4Ti3O12 (Bi3.4Dy0.6Ti3O12, BDT) ferroelectric thin films were deposited on Pt(111)/Ti/SiO2/Si(111) substrates by chemical solution deposition (CSD) and crystallized in nitrogen, air and oxygen atmospheres, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to identify the crystal structure, the surface and cross-section morphology of the deposited ferroelectric films. The results show that the crystallization atmosphere has significant effect on determining the crystallization and ferroelectric properties of the BDT films. The film crystallized in nitrogen at a relatively low temperature of 650 ℃, exhibits excellent crystallinity and ferroelectricity with a remanent polarization of 2Pr = 24.9 μC/cm2 and a coercive field of 144.5 kV/cm. While the films annealed in air and oxygen at 650 ℃ do not show good crystallinity and ferroelectricity until they are annealed at 700 ℃. The structure evolution and ferroelectric properties of BDT thin films annealed under different temperatures (600?750 ℃) were also investigated. The crystallinity of the BDT films is improved and the average grain size increases when the annealing temperature increases from 600 ℃ to 750 ℃ at an interval of 50 ℃. However, the polarization of the films is not monotonous function of the annealing temperature.
基金Project(05FJ2005) supported by the Key Project of Scientific and Technological Department of Hunan Province, China Project(05C095) supported by the Research Funds of Educational Department of Hunan Province, China Project(05JJ30208, 05JJ30126) supported by the Natural Science Foundation of Hunan Provincial , China
文摘The possibility of ultra-thin Y2O3 (yttrium sesquioxide) films as insulator of metal ferroelectric insulator semiconductor (MFIS) structure was investigated. The ultra-thin Y2O3 films with thickness of 10-40 nm were fabricated on p-type Si (100) substrates by molecular beam epitaxy(MBE) in vacuum and subsequently submitted to rapid thermal processing (RTP) in air ambient at 700, 800 and 900 ℃ for 30 min, respectively. The films were characterized by X-ray diffractometry and Raman spectroscopy. High frequency capacitance—voltage (C—V) characteristics and current—voltage (I—V) characteristics of the Y2O3/Si structure were analyzed. A Raman peak of the Y2O3 thin films was observed at 378 cm-1. From the C—V data, these films exhibit dielectric constants ranging from 13 to 17.28, the hysteresis width (△VFB) ranging from 0.07 to 0.22 V and the density of trapped charges ranging from 1.65×1011 to 4.01×1011 cm-2. A leakage current of 4.75×10-8 -9.0×10-6 A/cm2 at 1.5 MV/cm was observed. The results show that the Y2O3 buffer layers are suitable for non-volatile MFIS structure field-effect-transistors (FETs) memory application.
