Influence of electron trapping on domain dynamics in epitaxial Gunn diodes

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Abstract
Electron trapping has been observed in thin epitaxial Gunn diodes. This effect is significant as soon as the threshold field for domain build‐up is crossed. The field‐enhanced trapping appears to be strongly correlated with the thickness of the sample. Modification of domain dynamics, due to bidimensional and trapping effects, has been studied theoretically and experimentally, with low‐ and high‐impedance capacitive probes. Previous results on bistable switching have therefore been explained. The nature of traps has been investigated by means of photoluminescence experiments. Trapping appears to be linked with the presence of shallow acceptor levels (which are presumed to be silicon atoms on arsenic sites). The recent hypothesis of the existence of a localized silicon‐oxygen complex, behaving as a deep acceptor level in the crystal, fits closely with the present experiments.