Structural and electrical properties of SiNx:H films

Abstract

The electronic structure in off‐stoichiometric SiN_x:H films has been investigated using plasma‐deposited films prepared from a mixture of ammonia (NH₃) and silane (SiH₄) for various gas ratio R (=NH₃/SiH₄). Metal‐insulator‐metal diodes incorporating SiN_x:H films prepared using R values from 0.2 to 5 were fabricated and the electrical characteristics of these diodes were measured. The properties of the SiN_x:H films were also evaluated by ultraviolet‐visible, infrared, and x‐ray photoelectron spectroscopy. For the R range investigated, the optical band gaps and x values in the films varied from 1.6 to 3.6 eV and from 0.19 to 1.09, respectively. The hydrogen bonding configuration also changed from isolated Si—H bonds, with no adjacent Si—N bond, to multi‐N‐bonded Si—H bonds as R was increased. The anomalous behavior of the dynamic relative permittivity was observed and the existence of two traps with a different energy was deduced. The results of these electrical measurements are discussed and related to those of the compositional investigations.