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Semiconductors and Semiconductor Devices — Physics STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 SciencePhysicsSemiconductors and Semiconductor Devices1 Mark
Question
When a semiconducting material is doped with an impurity, new acceptor levels are created. In a particular thermal collision, a valence electron receives an energy equal to 2kT and just reaches one of the acceptor levels. Assuming that the energy of the electron was at the top edge of the valence band and that the temperature T is equal to 300K, find the energy of the acceptor levels above the valence band.
✓

Answer

2KT = Energy gap between acceptor band and valency band
$\Rightarrow2\times1.38\times10^{-23}\times300$
$\Rightarrow\text{E}=(2\times1.38\times3)\times10^{21}\text{J}$
$=\frac{6\times1.38}{1.6}\times\frac{10^{-21}}{10^{-19}}\text{eV}=\Big(\frac{6\times1.38}{1.6}\Big)\times10^{-2}\text{eV}$
$=5.175\times10^{-2}\text{eV}=51.75\text{meV}=50\text{meV}.$

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