Arsenic triselenide

Abstract: On evaporated layers of amorphous As2Se3 the photoconductivity is studied as a function of temperature and illumination intensity. An extremely slow decay of the photocurrent is found which is almost independent of temperature in the range of high excitation. At low excitation level the recombination is considerably enhanced with rising temperature. These results are discussed in the density of states model proposed by Marshall and Owen. It is shown that in the investigated temperature range recombination occurs directly between localized states. An aufgedampften Schichten von amorphem As2Se3 wird die Photoleitung in Abhangigkeit von der Temperatur und der Bestrahlungsstarke untersucht. Das Abklingen des Photostroms erfolgt auserordentlich langsam und hangt im Bereich hoher Anregung praktisch nicht von der Temperatur ab. Bei hohen Temperaturen im Bereich schwacher Anregung wird der Abklingvorgang mit steigender Temperatur deutlich schneller. Die Ergebnisse werden im Rahmen des von Marshall und Owen vorgeschlagenen Modells fur die Zustandsdichte diskutiert. Es wird gezeigt, das im untersuchten Temperaturbereich die Rekombination durch direkte Ubergange zwischen lokalisierten Zustanden erfolgt.

Abstract: Fresnel reflection at the boundary between two media of differing refractive indices is a major contributing factor to the overall loss in mid-infrared optical systems based on high-index materials such as chalcogenide glasses. In this paper, we present a study of broadband antireflective moth-eye structures directly nanoimprinted on the surfaces of arsenic triselenide (As2Se3)-based optical windows. Using rigorous coupled-wave analysis, we identify a relief design optimized for high transmittance ( 12%) in the 5.9–7.3 μm spectral range as well as improved omnidirectional properties. Finally, we demonstrate the adaptability of nanoimprinted surface reliefs by tailoring the nanostructure pitch and height, achieving both extremely broadband antireflective and highly efficient antireflective surface reliefs. The results and methods presented herein provide an efficient and scalable solution for improving the transmission of bulk optics, waveguides, and photonic devices in the mid-infrared.

Abstract: Observations of memory switching in thin films of amorphous As2Se3 have been made at various film thickness. The distribution of threshold voltages for a given thickness shows a strong peak which is attributed to the intrinsic switching mechanism. A plot of the most probable threshold voltage vs film thickness shows the switching process to be field controlled. Microscopic evidence is presented for strong Joule heating caused by capacitive discharge upon filament formation.

Abstract: Electric field enhanced phase separation has been examined in amorphous As2Se3 and has been found to be a viable switching mechanism for this material. A simple theoretical analysis of this process is developed in which the formation of dispersed As clusters precedes the growth of an As filament. The analysis predicts that the switching behavior is field controlled and that devices biased below the point at which they switch instantly will switch at a later time. Measurements of the time for memory switching have been made for a large number of devices biased below ``threshold'' and the mean time for switching has been found to increase exponentially with decreasing applied field.