????? 2 Semiconductor and P-N junction

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????? 2 Semiconductor and P-N junction
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Semiconductor material
Silicon wafer
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Semiconductor material
Silicon crystal
Sand 25 silicon
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Semiconductor material
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Silicon atom
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Intrinsic semiconductor
Silicon Crystal at T 0 K
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Energy gap
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Energy level
An electron-volt is the energy of an electron
that has been accelerated through a potential
difference of 1 volt, and 1eV 1.610-19 joules
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Intrinsic semiconductor
Silicon Crystal at T gt 0 K
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The Intrinsic Carrier Concentration
ni is the intrinsic carrier concentration
B is a
constant related to the specific semiconductor
material
Eg is the band-gap energy (eV)

T is the temperature (K)
k is
Boltzmanns constant (86 x 10-6eV/K)
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Electrical current
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Doping and Extrinsic Semiconductors
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Basic silicon doping
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?????????????????? (Diffusion) ?????????????? P-N
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Type of doping process
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???????????????????????? (Ion-Implantation)
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N-type semiconductor
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P-type semiconductor
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Thermal equilibrium
no thermal equilibrium concentration of free
electron po thermal equilibrium concentration
of hole
Silicon Crystal at T gt 0 K
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Thermal equilibrium (N-type)
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Thermal equilibrium (P-type)
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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Drift and Diffusion Currents
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P-N junction
Bell Labs the first transistor in December 1947.
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P-N Junction
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The Equilibrium P-N Junction
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The Equilibrium P-N Junction
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Built-in voltage
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P-N Junction biasing
Forward-bias
Non-bias
Reward-bias
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P-N Junction biasing
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Junction capacitance
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Reverse-Biased P-N Junction
Reward-bias
Cj Junction Capacitance Cj0 Junction
Capacitance at zero applied voltage VR Reverse
bias voltage Vbi built-in voltage
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Forward-Biased P-N Junction
Forward-bias
IS Reverse-bias Saturation current, in the
range of 10-15 to 10-13 VT Thermal voltage n
emission coefficient or ideality factor, in the
range 1 ? n ? 2
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Forward-Biased P-N Junction