Fig. 1

a Ideal DNA sample without disorder factors and without surrounding charges. b Illustrates an ideal n-type semiconductor DNA sample without disorder factors but it has surrounding charges. c represents a real n-type semiconductor DNA sample with both disorder factors and surrounding charges. They are five trapping levels lying above the valence band. One will denote them H1, H2, H3, H4, and H5. Note that this figure represents ideal n-type semiconductor, and the same assumptions are valid for p-type semiconductor