ON NON-OHMIC CONDUCTION AND THE THRESHOLD CHARACTERISTICS OF A BULK-TYPE SWITCHING DEVICE BASED ON THE CHALCOGENIDE GLASSY SEMICONDUCTOR AS0.40SE0.30TE0.30

The threshold characteristics of a switching device, based on a bulk semiconducting glass sample of composition As0.40Se0.30Te0. 30, have been examined. The experimental results are discussed in terms of the thermal breakdown model. The relationship between switching delay time and applied voltage is close to that predicted for the limiting case called impulse thermal breakdown. On the other hand, the dependence of threshold voltage on temperature correctly fits the one corresponding to steady-state thermal breakdown, confirming the fundamentally thermal nature of the electrical switching phenomenon. A non-ohmic process has been observed in the glass alloy under study (there are some signs of a space-charge limited current-type non-ohmic effect), although it does not play an important role in the switching effect. The weak field ohmic resistance-temperature characteristics are of the Arrhenius-type, an activation energy for the electrical conduction process of approximately 0.5 ev having been found. Last, the complete thermal balance equation has been numerically solved, and the results show good agreement with the experimental values.