Mechanical stress sensor of (n +)nanocrystalline/(p +)crystalline Si heterojunction

Abstract

A heterojunction of heavy phosphorus doped hydrogenated nanocrystalline Si film with heavy doped p-type crystalline Si wafer was prepared and measured to investigate mechanical stress effect on electronic characteristics. The yielded structure was demonstrated as a semiconductor backward diode according to current–voltage relation measurements, from where the absence of sequent resonance tunneling in conduction was also interpreted. Mechanical stress effect on electronic characteristics of the operated diode can be mainly ascribed to stress-induced bulk defect states instead of interface states, however, applied stress doesn't change conduction mechanism in this study. Soft breakdown in stressed junction was illustrated. Before breakdown the reverse operated current shows good linear dependence on applied stress with an effectual method of transforming mechanical signal to electronic one, which reveals the fabricated device as potential mechanical stress sensor in the future.