摘要:

Adaptive-learning neuron circuits are reviewed, in which a pulse frequency modulation (PFM) system is used and the interval of output pulses is changed through the learning process. Key devices of the circuits are MFSFETs (Metal Ferroelectric Semiconductor Field Effect Transistors). They are used for representing the synaptic weights of neurons and the polarity of the films is gradually changed by applying input pulses to the gates. In order to produce PFM signals, circuit using a UJT (unijunction transistor) is discussed. As a preliminary experiment for realization of MFSFETs, the electrical properties of metal ferroelectric metal (MFM) capacitor using sol-gel derived PZT films are discussed.

ISSN:1058-4587    

DOI:10.1080/10584589408019332

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Liquid Source Chemical Vapor Deposition (LSCVD) involves the use of sub-saturated aerosols of specially designed metallorganic precursors suitable for multicomponent oxide deposition in vacuum at room temperature. Materials of interest for ULSI DRAMs, such as Ba(1−x)SrxTiO3and SrTiO3show uniform deposition with microstructures optimized for step-coverage and small capacitor geometries. Electrical characteristics indicate capacitance densities of around 25–30 fF/um2and leakages in the order of 10−8A/um2. A review of these results and the LSCVD technique will be presented.

ISSN:1058-4587    

DOI:10.1080/10584589408019333

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Mechanisms of leakage currents and d.c. breakdown are reviewed for several high-dielectric films in prototype use for ULSI DRAMs, including barium strontium titanate, lead zirconate titanate, and proprietary materials, with special emphasis upon electrode interface phenomena. The early theory of Von Hippel is reviewed, and attention is paid to the modified boundary conditions to the thermal breakdown equation given below for the finite dimensions of capacitors in real ULSI DRAMs (EBis the breakdown field):

ISSN:1058-4587    

DOI:10.1080/10584589408019334

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

PbTiO3thin films on Si substrate were prepared by plasma enhanced chemical vapor deposition (PECVD) using Ti(O-i-C3H7)4, Pb(C2H5)4and oxygen. The composition of PECVD PbTiO3thin films was intensively influenced by the input flow rate ratio of precursors, while it was independent of the deposition temperatures. As-deposited PECVD PbTiO3thin film showed a uniform distribution of the Pb, Ti and C component throughout the bulk of film. The PECVD PbTiO3thin films after annealing at 650°C under O2ambient for 1 hr were converted from the amorphous phase to the crystalline perovskite phase. The phase transition between the tetragonal and the cubic phase occurred at about 500°C. The properties of thin films such as morphology, structure, dielectric constant, leakage current and P-E hysteresis-were also investigated.

ISSN:1058-4587    

DOI:10.1080/10584589408019335

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Pyroelectric infrared detectors based on La-modified PbTiO3(PLT) thin films have been fabricated by RF magnetron sputtering and micromachining technology. The detectors form PB1−xLaxTi1−x/4O3(x = 0.05) thin film ferroelectric capacitors epitaxially grown in-situ by RF magnetron sputtering on Pt/ MgO(100) substrate. The sputtered PLT thin film exhibits highly c-axis oriented crystal structure (90%) that poling treatment for sensing applications is not required. The c-axis orientation ratio a of deposited PLT thin film strongly depends on the morphology of Pt layer, which in turn varies with the thickness of Pt layer on MgO substrate. We have successfully grown highly c-axis oriented PLT film on Pt electrode with a conductive percolating network structure. Micromachining technology is used to lower the thermal mass of the detector by coating Polyimide on top of the sensing elements to support the fragile structure and by selectively etching the backside of the MgO substrate to reduce the heat loss. The sensing element exhibited a low noise equivalent power (NEP) of 1.7 × 10−10W and a very high detectivity D* value of 8.5 × 108cmVHz/W at room temperature. The high performance for pyroelectric infrared sensing is primarily due to the highly c-axis oriented PLT thin film and its minimized thermal mass.

ISSN:1058-4587    

DOI:10.1080/10584589408019336

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Defects of barium titanate thin films synthesized on Ti-deposited substrate by the hydrothermal method were defined by the heterogeneities of the surface morphology and phase-composition. In present work, the defects observed on the films have been classified, and the feature of these defects on the morphology and phase-composition summarized, and the formation process discussed. It has been proven experimentally that the homogeneity of the films was strongly affected by the surface state of the deposited Ti layer on the Si substrate and the reaction conditions. It is important to use a defectless and well-pretreated substrate and to process at high temperature above 180°C in the Ba(OH)2solution of high concentration for long enough reaction time and is an effective way to eliminate the defects.

ISSN:1058-4587    

DOI:10.1080/10584589408019337

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:1058-4587    

DOI:10.1080/10584589408019331

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor