Semi Conductors Objectives Part 07

121. When holes leave the p-material to fill electrons in the n-material the process is called diffusion.

122 . In case of selenium, under the influence of varying light intensity electrical conductivity changes.

123 . Diffusion current in a diode is caused by crystal formation.

124 . Depletion region in a PN diode is due to reverse biasing.

125 . Depletion region in a PN junction diode consists of fixed donor and acceptor ions.

126 . The photo electric current in amperes per watt of incident light depend on frequency of incident light.

127 . When a diode is forward biased barrier potential decrease.

128 . In case of photo conductor for Germanium when forbidden energy gap is 0.72 eV, the critical wavelength for intrinsic excitation will be 1.73 micro m.

129 . The work function of a photo surface whose threshold wave length is 12,00 A, will be 1.03eV.

130 . A potential difference is developed across a current carrying metal strip when the strip is placed in a transverse magnetic field”. The above effect is known as Hall’s effect.

`131 . As the temperature of a semi-conductor is reduced to absolute zero all valance electrons tend to remain in the valance band.

132 . Carbon belongs to the same group of periodic table as that of Germanium and Silicon.

133 . The crystal structure of silicon is diamond.

134 . Forbidden energy gap is highest for Gallium arsenide.

135 . Silicon semi-conductor has the highest melting point.

136 . The minimum charge carried by an ion is equal to the charge of an electron.

137 . The electrons in an atom moves in elliptical orbits.

138 . The impurity added to extrinsic semi-conductor is of the order of 1 in 100,000,000.

139 . The mean life time of the minority carriers is in the range of a few nano seconds.

140 . For insulators the energy gap is of the order of 5 to 15eV.