Question

Consider a semiconducting material. What will be the energy of electrons and holes that constitute

excitons? Let m = rest mass of free electron, ε = dielectric constant = 15, Δ = 1.5 eV. Determine the

temperature at which excitons will be formed?

Answer 1

$$E(n)=-\frac{1}{n^2}\frac{\mu R_y}{m_0\epsilon_r^2}$$

where ${\displaystyle {\text{Ry}}}$ is the Rydberg unit of energy,

$${\displaystyle \varepsilon _{r}}$$

is the relative permittivity,

$${\displaystyle \mu =\frac{(m_{e}^{*}m_{h}^{*})}{(m_{e}^{*}+m_{h}^{*})}}$$

is the reduced mass of the electron and hole, and m₀ is the electron mass.