Contribution of light holes to thermionic field emission in Si and Ge

Light holes (LH) may give the main contribution to the thermionic field-emission (TFE) current through grain boundaries in Si and Ge. In spite of only a small concentration, the LH dominate because their transmission probability through the potential barrier may be several orders of magnitude larger than the probability for the heavy holes (HH). In order to explain the temperature dependence of the TFE current, previous authors were forced to introduce a lowering of the potential barrier with decreasing temperature. However, taking into account the contribution of the LH in TFE is equivalent to a lowering of the potential barrier because it results in a slower decrease of the current than found in previous calculations with only one type of holes.