Terahertz Luminescence and Electrical Characteristics of SiC Structures with Natural Superlattice in Strong Electric Fields

Abstract

Recently, the intense terahertz electroluminescence from monopolar n++–n−–n+ structures of 8H-SiC natural superlattice at helium temperatures due to Bloch oscillations was found out. In the present work, we compare the THz emission and electrical characteristics of monopolar n++–n−–n+ and bipolar n++–π–n+ 8H-SiC structures at 7 K. The bipolar n++–π–n+ 8H-SiC structures were analogous to those on which the negative differential conductivity effect was observed earlier for three polytypes (4H, 6H, and 8H) at T = 300 K. The obtained results allow one to draw a conclusion about common nature of the negative differential conductivity and THz emission effects in the natural superlattice of SiC caused by Bloch oscillations. These results give the proof of fundamental importance supporting the objectivity of postulates of the F. Bloch – C. Zener – G. N. Wannier theory