Jack Reynolds

Faculty Sponsor: John Yukich

This experiment studies a quantum phenomenon that arises in transistors. The experiment attempts to accurately measure the band gap in silicon and germanium transistors by examining the relationship between the collector current and the base-emitter voltage. This band gap energy is essentially the quantum effect that there can be no particles in the energy states within the gap. The canonical distribution shows by way of statistical mechanics that the maximum current, I0, will be proportional to e-E/kT, where E is the band gap energy, k is Boltzmann’s constant, and T is the temperature in Kelvin. Thus, a plot of ln(I0) vs. 1/T will reveal a slope of -E/k, from which E can be determined. This experiment makes use of liquid nitrogen, dry ice, water ice, a warm water bath, and room temperature conditions in order to attain at least five temperatures at which to take data. This amount of data will allow for great precision and accuracy, and reveal nearly exactly the energy gap values, as well as expose more fully the nuances of transistor materials and the characteristics of their materials