Question

The energy gap in a semiconductor

• A. Increases with temperature
• B. Does not change with temperature
• C. Decreases with temperature
• D. Is zero

Answer 1

Answer: (C)

Decreases with temperature

The energy bandgap of semiconductors tends to decrease as the temperature is increased. the interatomic spacing increases when the amplitude of the atomic vibrations increases due to the increased thermal energy. This effect is quantified by the linear expansion coefficient of a material. An increased interatomic spacing decreases the potential seen by the electrons in the material, which in turn reduces the size of the energy bandgap. A direct modulation of the interatomic distance, such as by applying high compressive (tensile) stress, also causes an increase (decrease) of the bandgap.

The variance of energy gap with temperature is given by

$E_g\left(T\right)=E_g\left(0\right)-\frac{\alpha T^2}{T+\beta }$