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    October 18, 2013 ELECTRONIC DEVICES 1

    Electronic DevicesCourse No. : EEE F214 / ECE F214 / EEE C381

    Course Instructor : Prabhakara Rao

    Email : budhiraju@bits-hyderabad.ac.in

    Room No. : D305

    Department of EEEBITS-Pilani, Hyderabad Campus

    mailto:budhiraju@bits-hyderabad.ac.inmailto:budhiraju@bits-hyderabad.ac.inmailto:budhiraju@bits-hyderabad.ac.inmailto:budhiraju@bits-hyderabad.ac.in
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    October 18, 2013 ELECTRONIC DEVICES 2

    For a hypothetical semiconductor, we have n

    = p = 1000 cm2 / V.s and Nc = Nv = 10

    19 / cm3.

    If the conductivity of the intrinsic

    semiconductor at 300 K is 4 X 10-6 (-cm)-1.What is the conductivity at 600 K.

    Problem

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    October 18, 2013 ELECTRONIC DEVICES 3

    Ans - Problem 9

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    October 18, 2013 ELECTRONIC DEVICES 4

    Crystal Lattices

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    October 18, 2013 ELECTRONIC DEVICES 5

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    October 18, 2013 ELECTRONIC DEVICES 6

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    7/41October 18, 2013 ELECTRONIC DEVICES 7

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    8/41October 18, 2013 ELECTRONIC DEVICES 8

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    9/41October 18, 2013 ELECTRONIC DEVICES 9

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    10/41October 18, 2013 ELECTRONIC DEVICES 10

    Body Centered Cubic

    Atoms are arranged at the corners of the cube

    with another atom at the cube center.

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    11/41October 18, 2013 ELECTRONIC DEVICES 11

    Body Centered Cubic

    Since atoms are assumed to touch along the

    cube diagonal in BCC, the lattice parameter is

    related to atomic radius through:

    3

    4Ra

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    Body Centered Cubic

    Coordination number for BCC is 8. Each

    center atom is surrounded by the eight corner

    atoms. The lower coordination number also results in

    a slightly lower APF for BCC structures. BCC

    has an APF of 0.68, rather than 0.74 in FCC

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    Atomic Packing Factor: the ratio of atomicsphere volume to unit cell volume, assuming a

    hard sphere model.

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    Face Centered Cubic (FCC)

    Atoms are arranged at the corners and centerof each cube face of the cell.

    Atoms are assumed to touch along face diagonals

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    The lattice parameter, a, is related to the

    radius of the atom in the cell through:

    Coordination number: the number of nearestneighbors to any atom. For FCC systems, the

    coordination number is 12.

    22Ra

    Face Centered Cubic (FCC)

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    Crystallographic Directions

    Cubic systems

    directions are named based upon the projection

    of a vector from the origin of the crystal to

    another point in the cell.

    Conventionally, a right hand Cartesian

    coordinate system is used.

    The chosen origin is arbitrary, but is always

    selected for the easiest solution to the problem.

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    Crystallographic Directions

    Points within the lattice are written in the

    form h,k,l, where the three indices

    correspond to the fraction of the lattice

    parameters in the x,y,z direction.

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    October 18, 2013 ELECTRONIC DEVICES 19

    Miller Indices

    Indices are written in square brackets

    without commas (ex: [hkl])

    Negative values are written with a barover the integer.

    Ex: if h

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    October 18, 2013 ELECTRONIC DEVICES 20

    Specify the directions using Millerindices

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    October 18, 2013 ELECTRONIC DEVICES 21

    Ans

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    October 18, 2013 ELECTRONIC DEVICES 22

    Miller Indices

    Crystallographic Planes

    Identify the coordinate intercepts of the plane

    the coordinates at which the plane intercepts the x, yand z axes.

    If a plane is parallel to an axis, its intercept is taken as

    .

    If a plane passes through the origin, choose anequivalent plane, or move the origin

    Take the reciprocal of the intercepts

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    October 18, 2013 ELECTRONIC DEVICES 23

    Miller Indices

    Clear fractions due to the reciprocal, but do notreduce to lowest integer values.

    Planes are written in parentheses, with bars over

    the negative indices.

    Ex: (hkl) or if h

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    October 18, 2013 ELECTRONIC DEVICES 24

    Example

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    October 18, 2013 ELECTRONIC DEVICES 25

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