Objective: Determination of Energy Band Gap of Silicon, Germanium etc using diodes and light emitting diodes.
Forbidden Energy Gap Kit
Objective: Determination of Energy Band Gap of Silicon, Germanium etc using diodes and light emitting diodes. Theory: The current-voltage characteristic of a p-n junction can be described by the ideal diode equation Considering the diode in forward bias, 1 can be neglected in above equation. is proportional to the Boltzmann factor and to where is a constant. We may thus write Neglecting the dependence of as compared to the exponential dependence on T and can treat B = A as almost constant. Therefore, Combining Eqs. (1) and (2), and neglect 1 in Eq. (2), we obtain Experimentally if the current I is constant, above equation may be rewritten as where C=ln(I/B). If we rewrite Eq. (3), we have which is the linear relation, provided that is constant. If we compare Eqs. (4) and (1), we see that intercept and slope We divide b by a and obtain Equation (5) relates the band gap energy to the experimentally determined values of the parameters a and b in Eq. (1). The Setup facilitates determination of Energy Band Gap of semiconductors by measuring the voltage drop across sample at a constant current. A graph of V vs T^{1} is plotted and ratio of its slope and intercept gives the value of Energy Gap as per equation (5).