Question
In a pure Ge sample at room temperature the electron and hole concentration is each equal to . It is doped with indium, 1 indium atom is added for 10^{6} Ge atoms. Find the conductivity of doped Ge. The concentration of Ge atoms in the sample is . Given :
.

None of these



diffcult
Solution
The concentration of indium (acceptor) atoms in the sample is
.
Since one acceptor atom provides one hole, the concentration of the holes provides is , that is
.
For a doped semiconductor, we have
,
Where n_{i} is the intrinsic concentration. Thus, the electron concentration in the doped semiconductor is
.
The electrical conductivity of the doped Ge is given by
]
SIMILAR QUESTIONS
Pure Si at 300 K has equal electron (n_{e}) and hole (n_{h}) concentrations of . Doping by indium increases n_{h} to . Calculate n_{e} in the dopped Si.
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The number of electronhole pairs in an intrinsic semiconductor is at 27^{o}C. If this semiconductor is doped by a donor impurity such that the number of conduction electrons becomes, calculate the number of holes at 27^{o}C. Also calculate the dopant concentration.
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A semiconductor is known to have an electron concentration of and a hole concentration of . Is the semiconductor ntype or ptype? What is the resistivity of the sample if the electron mobility is 23,000 cm^{2}V^{–1}s^{–1} and hole mobility is 100 cm^{2}V^{–1}s^{–1}.
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.
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