Radiation emission during the on state in a noncrystalline chalcogenide threshold switch

Two types of radiation emission have been detected during the on state of threshold switching events in noncrystalline chalcogenide thin films having a transparent SnO2 (NESA) bottom electrode and a heat conducting top electrode. The common form of the radiation is an emission at about 1.2–1.4 μm which (i) is propagated through a wide solid angle, (ii) is relatively independent of time during the on-state pulse (iii) has an integrated intensity which is approximately a linear function of on-state power and a superlinear function of on-state current, and (iv) requires a minimum on-state current for initiation. The second type of emission is between 0.75 and 3 μm and is detected rather rarely. This latter emission has a characteristic intensity which is a steeply peaked function of on-state time and appears to be possibly highly collimated. The peaked emission has been detected in pulsed modes using single set pulses and has also been detected continuously using low-frequency repetitive threshold set pulses. Both radiation effects appear to be nonthermal in origin.