Spontaneous resistance oscillations inp-germanium at low temperatures and their spatial correlation

Abstract

Spontaneous oscillations and chaotic behavior of the electric resistance can be observed inp-doped germanium during avalanche breakdown at liquid-He temperatures. By a series of different ohmic contacts attached to the specimen surface, the spatial coupling between the resistance oscillations in different sections of the same single-crystalline Ge sample can be studied. Using a geometry where coupling via charge carriers can be ignored, we have investigated the case where the lattice heat conductivity of the Ge crystal represents the dominant coupling mechanism. If two coupled sample sections were operated in the post-breakdown regime, a distinct phase shift developed between the current oscillations in both sections eventually reaching exact phase reversal. These results show a striking similarity to the dynamics of a coupled Rashevsky-Turing reaction-diffusion system.