Observation of negative differential resistance in SiO2/Si heterostructures

The negative differential resistance (NDR) effect been widely reported in the physical systems of traditional semiconductors, and corresponding theoretical mechanisms are known and applied. However, exploring the origin of NDR phenomena emerging in new structures or conditions remains a worthwhile challenge. Here, we report an experimental observation of an NDR effect based on SiO2/Si heterojunctions by injecting photo-generated carriers via vacuum ultraviolet (VUV) irradiation. We propose a complex competition mechanism between trap centers' and recombination centers' dominating carrier transport behavior. This is caused by the difference in spatial distribution of density of band-tail states and defect states in SiO2/Si. This work may inspire further consideration of SiO2/Si heterojunctions for electronic applications.