Electron-trapping-triggered anneal of defect states in silicon-rich hydrogenated amorphous silicon nitride

Abstract

The dc-current stress behavior of Mo/a-SiNxHy/Mo thin-film diodes is discussed for several a-SiNxHy-plasma-deposition conditions. Current transport is governed by thermionic field emission of electrons over a reverse biased Schottky barrier. The barrier height is determined by the a-SiNxHy-plasma-deposition conditions. Therefore these back-to-back Schottky devices provide an elegant way to perform dc-current stressing at several well defined carrier densities for similar stress fields. It is shown that such experiments allow assessment of defect-state creation/anneal mechanisms in a-SiNxHy. An electron-trapping-triggered anneal mechanism accounts for the observed dependence of the defect density at the electrode injecting contact (cathode) on the hole-barrier height at the anode. Also a new microscopically detailed anneal reaction scheme is proposed. The defect-state creation/anneal mechanism is expected to be generally applicable for all silicon-rich hydrogenated amorphous silicon alloys.

High stability amorphous-silicon–nitride thin-film diode ring switch

“…A further reduction of the drift can be obtained by preaging the TFDs in antiparallel configuration: in this case, a strong preage of 6000 C/cm 2 resulted in a complete elimination of the drift. This result may be understood as the cathodic drift is observed to saturate after the passage of a certain amount of current, 6,7 whereas the anodic drift, which continues to increase over longer time scales, is effectively avoided in the antiparallel configuration.…”

“…These barriers may be measured by activation energy measurements (E a ) or by Tauc optical band-gap (E T ) measurements (E h ϭE T ϪE a ). 7 In Fig. 1, we see that by changing the process conditions it is possible to independently vary E h , E T , and also E a .…”

“…3,4 In recent articles, the optimization of the material deposition conditions and the occurrence of several carrier-induced state creation mechanisms were assessed for a-SiN x H y TFDs. [5][6][7] In this letter, the implications of the obtained results for the design of a thin-film diode ring switch with very stable switching characteristics is discussed.…”

“…For a low defect state creation, it is necessary to use a material with a large E h . 7 A stable TFD would, therefore, have the largest possible E h for a given E a . As TFDs are designed to operated in an ac mode, state creation at the anode of the TFD needs to be considered as well.…”

“…7 State creation is driven by electron-hole recombination, while defect annealing is electron trapping triggered. The local hole density determines the equilibrium defect density.…”