材料的电学性质ppt课件
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材料的电学性质
Content
Electrical conduction Energy band structures in solids Electron mobility Semiconductivity The hall effect Semiconductor devices Dielectric behavior
Electrical conduction
Material Metal Semiconductor Insulator
Conductivity/(Ωm)-1 On the order of 107 10-6~104 10-10~10-20
Energy band structures in solids
Schematic representation of the relative energies of the electrons for the various shells and subshells
12
Impurity level Impurity level
P-type Semi-
Intrinsic Semi-
Holes (in addition to free electrons) are created in semiconductors and insulators when electron transitions occur from filled states in the valence band to empty states in the conduction band. In metals, electron transitions normally occur from empty to filled states within the same band, without the creation of holes.
Semiconductivity
Intrinsic semi-conductors are those in which the electrical behavior is based on the electronic structure inherent in the pure material. When the electrical characteristics are dictated by impurity atoms, the semiconductor is said to be extrinsic.
is an indication of the frequency of scattering events; its units are square meters per volt-second (m2/V-s).
Thermal resistivity contribution
where ρo and a are constants for each particular metal.
Electron mobility
E F but
I Because t
By imperfections in the crystal lattice, including impurity atoms, vacancies, interstitial atoms, dislocations, and even the thermal vibrations of the atoms themselves.
N-type SemiExtrinsic Semi-
Metal
Insulator
Femi level
(1) Energy diagram of a metal, an insulator, and semiconductor
Fermi Level: The energy level corresponding to the highest filled state at 0 K. The Eg >2ev in insulator and Eg< 2 ev in Semiconductor.
the number of electrons in the conduction band far exceeds the number of holes in the valence band (or ) (Come from the phosphorus atom doped)
Holes are present in much higher concentrations than electrons (i.e., ( come from boron atom doped)
where the V’s and ρ’s represent volume fractions and individual resistivities for the respective phases.
in which and represent the individual thermal, impurity, and deformation resistivity contributions, respectively.
Impurity resistivity contribution
where A is a composition-independent constant that is a function of both the impurity and host metals. ci (at%)
Deformation resistivity contribution
)
The temperature dependence of carrier concentration
Influence of dopant content
The hall effect
Semiconductor devices
wenku.baidu.com
The primary difference is that the gate current is exceedingly small in comparison to the base current of a junction transistor. MOSFETs are, therefore, used where the signal sources to be amplified cannot sustain an appreciable current. Another important difference between MOSFETs and junction transistors is that, although majority carriers dominate in the functioning of MOSFETs (i.e., holes for the depletion-mode p -type MOSFET of , minority carriers do play a role with junction transistors.
Content
Electrical conduction Energy band structures in solids Electron mobility Semiconductivity The hall effect Semiconductor devices Dielectric behavior
Electrical conduction
Material Metal Semiconductor Insulator
Conductivity/(Ωm)-1 On the order of 107 10-6~104 10-10~10-20
Energy band structures in solids
Schematic representation of the relative energies of the electrons for the various shells and subshells
12
Impurity level Impurity level
P-type Semi-
Intrinsic Semi-
Holes (in addition to free electrons) are created in semiconductors and insulators when electron transitions occur from filled states in the valence band to empty states in the conduction band. In metals, electron transitions normally occur from empty to filled states within the same band, without the creation of holes.
Semiconductivity
Intrinsic semi-conductors are those in which the electrical behavior is based on the electronic structure inherent in the pure material. When the electrical characteristics are dictated by impurity atoms, the semiconductor is said to be extrinsic.
is an indication of the frequency of scattering events; its units are square meters per volt-second (m2/V-s).
Thermal resistivity contribution
where ρo and a are constants for each particular metal.
Electron mobility
E F but
I Because t
By imperfections in the crystal lattice, including impurity atoms, vacancies, interstitial atoms, dislocations, and even the thermal vibrations of the atoms themselves.
N-type SemiExtrinsic Semi-
Metal
Insulator
Femi level
(1) Energy diagram of a metal, an insulator, and semiconductor
Fermi Level: The energy level corresponding to the highest filled state at 0 K. The Eg >2ev in insulator and Eg< 2 ev in Semiconductor.
the number of electrons in the conduction band far exceeds the number of holes in the valence band (or ) (Come from the phosphorus atom doped)
Holes are present in much higher concentrations than electrons (i.e., ( come from boron atom doped)
where the V’s and ρ’s represent volume fractions and individual resistivities for the respective phases.
in which and represent the individual thermal, impurity, and deformation resistivity contributions, respectively.
Impurity resistivity contribution
where A is a composition-independent constant that is a function of both the impurity and host metals. ci (at%)
Deformation resistivity contribution
)
The temperature dependence of carrier concentration
Influence of dopant content
The hall effect
Semiconductor devices
wenku.baidu.com
The primary difference is that the gate current is exceedingly small in comparison to the base current of a junction transistor. MOSFETs are, therefore, used where the signal sources to be amplified cannot sustain an appreciable current. Another important difference between MOSFETs and junction transistors is that, although majority carriers dominate in the functioning of MOSFETs (i.e., holes for the depletion-mode p -type MOSFET of , minority carriers do play a role with junction transistors.