Charge transport diagnosis by: I-V(resistivity), screening and Debye length, mean free path, Mott effect and Bohr radius in InAs, In_(0.53)Ga_(0.47)As and GaAs MBE epitaxial layers

摘要

We propose using collected galvano-magnetic data on MBE samples of n-type undoped epi-layers of InAs, In_(0.57)Ga_(0.47)As and GaAs on InP semi-insulating and GaAs semi-insulating substrates to characterize their charge transport properties. Hall concentration and resistance measurements vs. temperature were carried out, and these results allowed us to calculate the mean free path and magnetic length. However, they are mono-crystalline, they present multi-component charge transport structures. The characterization of these layers by means of a combined analysis of galvano-magnetic properties, I-V (resistivity), screening and Debye length, mean free path, Mott effect and Bohr radius characteristics gave new and very interesting results. The application of a previously described method of analysis also allows for the presence of a Mott transition to be determined. The presence of a Mott transition leads to the hypothesis that a part of conductance in such layers, especially at low temperatures may be due to an impurity band. We suppose either that during their epitaxial growth all of the investigated layers were unintentionally doped with excess atoms of one component, vacancies of other or that dangling bonds are present. Therefore, in the range of low temperatures, the possible and dominant conduction mechanism is conduction via such defects, with electrons moving by thermally activated hopping.