210 research outputs found

    HUBUNGAN ANTARA SELF-REGULATED LEARNING DENGAN DISIPLIN BELAJAR SISWA

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    Penelitian ini dilatarbelakangi oleh rendahnya kedisiplinan siswa yang belum dapat menerapkan disiplin belajar yang baik di sekolah. Self-regulated learning merupakan strategi yang dapat membantu siswa untuk mampu berdisiplin dengan mengatur dan mengarahkan dirinya. Penelitian ini bertujuan untuk mengetahui hubungan antara self-regulated learning dengan disiplin belajar siswa kelas XI SMK Negeri 12 Bandung. Pendekatan kuantitatif dan metode deskriptif korelasional digunakan dalam penelitian ini. Populasi berjumlah 388 siswa, sedangkan sampel sebanyak 196 siswa yang diambil dengan menggunakan teknik simple random sampling. Data yang dikumpulkan diperoleh dari hasil penyebaran instrumen angket yang terdiri dari dua variabel yaitu self-regulated learning dan disiplin belajar siswa. Hasil penelitian menunjukkan bahwa (1) self-regulated learning siswa berada pada kategori sedang dengan presentase sebesar 58,4% (2) disiplin belajar siswa berada pada kategori sedang dengan presentase sebesar 51,3% (3) hasil korelasi product moment diperoleh rxy= 0,276 ini menunjukkan korelasi positif yang signifikan artinya terdapat hubungan yang berarti antara self-regulated learning dengan disiplin belajar siswa di SMK Negeri 12 Bandung. Hasil uji signifikansi didapatkan koefisien korelasi sebesar 3,999 > 1,65 maka hipotesis H0 ditolak dan H1 diterima dengan koefisien determinasi sebesar 7,61%. Adapun rekomendasi sebagai tindak lanjut penelitian ditujukan kepada guru bimbingan dan konseling dan peneliti selanjutnya. ;---This research is grounded by the lack of students’ discipline who cannot implement a good learning discipline at school. Self-regulated learning is a strategy which can help students to be able to discipline by managing and directing themselves. This research aims to identify the correlation between self-regulated learning and learning discipline of eleven grade students in SMK Negeri 12 Bandung. Both quantitative approach and descriptive-correlational method were used in this research. The number of the population were 388 students, while the number of the sample by using simple random sampling were 196 students. The collected-data of the result of administering questionnaire consisting of two variables which were self-regulated learning and the students’ learning discipline. The findings showed that (1) self-regulated learning students was mostly the middle category with the percentage of 58.4% (2) the students’ learning discipline was mostly the middle category with the percentage of 51.3% (3) the calculation result by using product moment correlation formula with rxy= 0.276 showed positive correlation signifying which meant there was significant correlation between self-regulated learning and student’s learning discipline in SMK Negeri 12 Bandung. The significance test revealed that correlation coefficient is 3,999 > 1,65 in this regard, H0 hypothesis was rejected while H1 was accepted with determination coefficient of 7,61%. In addition, the recommendation of this research as a follow-up of the research is addressed to a guidance and counseling teacher and the next researcher

    Growth Route Toward III-V Multispectral Solar Cells on Silicon

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    To date, high efficiency multijunction solar cells have been developed on Ge or GaAs substrates for space applications, and terrestrial applications are hampered by high fabrication costs. In order to reduce this cost, we propose a breakthrough technique of III-V compound heteroepitaxy on Si substrates without generation of defects critical to PV applications. With this technique we expect to achieve perfect integration of heterogeneous Ga1-xInxAs micro-crystals on Si substrates. In this paper, we show that this is the case for x=0. GaAs crystals were grown by Epitaxial Lateral Overgrowth on Si (100) wafers covered with a thin SiO2 nanostructured layer. The cristallographic structure of these crystals is analysed by MEB and TEM imaging. Micro-Raman and Micro-Photomuminescence spectra of GaAs crystals grown with different conditions are compared with those of a reference GaAs wafer in order to have more insight on eventual local strains and their cristallinity. This work aims at developping building blocks to further develop a GaAs/Si tandem demonstrator with a potential conversion efficiency of 29.6% under AM1.5G spectrum without concentration, as inferred from our realistic modeling. This paper shows that Epitaxial Lateral Overgrowth has a very interesting potential to develop multijunction solar cells on silicon approaching the today 30.3% world record of a GaInP/GaAs tandem cell under the same illumination conditions, but on a costlier substrate than silicon.Comment: Preprint of the 28th EUPVSEC proceedings, September 2013, Paris, France. (5 pages

    Novel approach for displacement and strain mapping from HR-(S)TEM images of crystalline materials: Absolute quantitative mapping of strain and displacement fields in HR-TEM and HR-STEM images of crystals with reference to a virtual real lattice

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    International audienceA large number of nanostructures of different type (precipitates, nanocrystals, 3D islands and 2D layers) are widely used in modern microelectronics. For example, Si and Ge nanocrystals buried in the gate oxide of MOSFET transistors are promising candidates for the large-scale, low-power integration in non-volatile semiconductor nanomemories. Metal Ag and Ag doped nanoparticles embedded into a dielectric matrix or AsSb nanoinclusions buried in the low-temperature grown (Al, Ga)(As, Sb) semiconductor films can be used to enhance and manipulate electromagnetic fields. The localization of electrons and holes within self-assembled epitaxial InGaAs quantum dots offers fascinating opportunities for both basic and applied research. Chemical composition, unit cell structure, and intrinsic strain all influence the optical and electrical properties of such nanostructures. As a result, such parameters should be assessed with subnanometer spatial resolution and high precision.Strain and atom displacements are particularly concerned in complex oxides because they alter spontaneous polarization and may result in the polarization reversal. Complex oxides are made up of more than two types of sublattices, each of which can be strained and/or shifted differently, although sharing a common Bravais lattice. Thus, strain and atomic displacements must be measured for each sub-lattice individually and in relation to others.Here, we propose a method for the reciprocal space treatment of high-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning transmission electron microscopy (HR-STEM) images. Named “Absolute strain” (AbStrain), it allows for quantification and mapping of interplanar distances and angles, displacement fields and strain tensor components with reference to a user-defined virtual real lattice, as well as for their correction from the image distortions specific to HR-TEM and HR-STEM imaging. The mathematical formalism for AbStrain will be presented. When a crystal is made up of two or more types of atoms, the technique for extracting images of the sub-lattices and measuring absolute and polarization related displacements will be described. We will demonstrate a successful application of AbStrain to HR-TEM and HR-STEM images of nanocrystals and nanolayers. The advantages of AbStrain with respect to existing methods like geometric phase analysis and “peak finding” will be discussed

    Quantitative mapping of strain and displacement fields in complex oxides by STEM studies

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    International audienceComplex oxides, which have a wide range of characteristics, have a lot of potential in the microelectronics industry. They are made up of two or more types of atoms, each of which has its own sublattice constraint. However, the epitaxial integration of piezoelectric and ferroelectric crystals results in a variety of material properties being altered. The ability to measure polarization locally is therefore essential for furthering understanding. Scanning transmission electron microscopy (STEM) is a versatile tool which provides nanoscale information on structural and chemical properties. Here, we present different developments on the analysis of STEM images in the aim to study piezoelectric and ferroelectric materials.Strain and atom displacements are particularly concerned because they alter spontaneous polarization and may result in the creation of inverse polarization domains. The deformed sub-lattices can be strained and/or shifted differently, although sharing a common Bravais lattice. Thus, atomic displacements must be measured for each sub-lattice individually and in relation to others. Such an objective can be achieved by a treatment of high-resolution STEM (HR-STEM) images which allows direct visualization of atomic columns in a crystal. In order to quantify their positions in the image, a real-space method called "peak findings" has been used thus far. One of the method's major flaws is its small field of view (15 nm x 15 nm). Here, we present AbSTEM, a method for HR-STEM image treatment in reciprocal space that allows: i) extraction of sub-lattice images; ii) absolute correction of an ensemble of distortions present in HR-STEM image; iii) mapping of absolute values of interplanar distances and angles, strain tensor components, and displacements measured for each sub-lattice individually and in relation to others, all with high precision and accuracy for large (60 nm x 60 nm) field of view. The limits of the technique will be discussed
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