S. L. Arora Solutions for Chapter: Semiconductor Devices and Digital Circuits, Exercise 1: Problems For Practice

If the energy of a photon of sodium light $(\mathrm{\lambda }=589 \mathrm{n}\mathrm{m})$ equals the band gap of a semiconductor, calculate the minimum energy required to create hole-electron pair. Take, $h = 6.6\times {10}^{-34} \mathrm{Js}, c = 3\times {10}^8 \mathrm{m}/\mathrm{s}$

A doped semiconductor has impurity levels $30 \mathrm{m}\mathrm{e}\mathrm{V}$ below the conduction band. Is the material $\mathrm{n}$-type or $\mathrm{p}$-type? Find the maximum wavelength of light so that an electron of impurity level is just able to jump into conduction band.

The band gap of an alloy semiconductor gallium arsenide phosphide is $1.98 \mathrm{e}\mathrm{V}.$ Calculate the wavelength of radiation that is emitted when electrons and holes in this material combine directly. What is the colour of the emitted radiation? Take $\mathrm{h}=6.6\times {10}^{-34}\mathrm{J}\mathrm{s}, \mathrm{c} = 3\times {10}^8 \mathrm{m}/\mathrm{s}$

Pure silicon at $300 \mathrm{K}$ has equal electron and hole concentrations of $1.5\times {10}^{16} {\mathrm{m}}^{-3}.$ Doping by indium increases the hole concentration to $4.5\times {10}^{22} {\mathrm{m}}^{-3}.$ Calculate the new electron concentration in the doped silicon.