Technology Research Of Photo-induced Effects In As-s Amorphous Semiconductor Films

Amorphous chalcogenide glasses are potentially useful materials for IR waveguides, offering both high transparency in the near and far infrared. It possesses much lower intrinsic loss, and merits of the fabrication of the optical waveguide. These materials have therefore attracted considerable interest in recent years. Under light irradiation, especially, Amorphous chalcogenide semiconductor have many photo-induced effects which are applied widely in many major, including optical waveguide, optoelectronic integrated technology, thermal imaging technology, far distance sensor and coupling apparatus, and so on. This paper studies mainly on the application of amorphous As₂S₈ in integrated optics.At first, the planar waveguide theory and prism coupling theory are introduced briefly, and how to use the prism coupling technique for the measurement of the refractive index and the film thickness is narrated concisely in this paper.It is considered that the molecular conformation model of the as-deposited As₂S₈ film is consist of lone-pair electron, valence-alternation pair ( C₃⁺ C₁^- ), chain-structure S-S bonds, and pyramidal configuration As-S in this paper, so the energy gap model of As₂S₈ is built. That the molecules of As₂S₈ have more sulfur atom action intensity than those of other materials (As₂S₃, As₁S₉ and As₃S₇) can explain reasonably the optical stopping effect of As₂S₈ film, which is not observed in As₂S₃, As₁S₉ and As₃S₇ film. Besides light pump action, the optical stopping effect lies on sulfur atom action intensity, the degrees of making sublevels, and the densities of these sublevels. In the optical stopping effect process, the band gap light and the sub-band gap light, accumulates and consumes sublevel electrons, respectively.In the aspect of the study on the photo-induced structure changes of As₂S₈ film, the photoinduced refractive index and film thickness changes are observed in As₂S₈ film under the light irradiation, the annealing treatment and the correlation action of light and annealing treatment. The refractive index of the as-deposited As₂S₈ film increases, and gets to saturation-like limit at last under an ultraviolet (UV) light irradiation. The refractive index of the annealed As₂S₈ film comes back completely after being annealed in near Tg (glass transition temperature). The film thickness of the as-deposited and annealed As₂S₈ film decreases as exposure proceeds, which implies that the volume of the As₂S₈ film is shortened. The fabrication techniques of As₂S₈ stripe waveguide are reported. An UV irradiation technique is presented and applied successfully As₂S₈ stripe waveguide preparation. The optical stopping effect of As₂S₈ stripe waveguide under irradiationin of the bandgap light (He-Cd laser) is investigated, and it is confirmed that this device exhibits useful switching functionality based on the photo-optical effect.A new optical-stopping waveguide device is designed and fabricated on the basis of the optical stopping effect in the As₂S₈ stripe waveguide. The design of a LiNbO3-As₂S₈ compound waveguide device with the optical-stopping function is presented, which can realize three values in synapse weighting effect of the optical neural device, positive, zero and negative value, respectively.In the end, the photovoltaic effect of the As₂S₈ film is reported, and it is pointed out that the mechanism of the"enhancement"of photovoltage by He-Ne laser light which has much lower energy that the energy corresponding to the transmission is perhaps consistent with that of the optical stopping effect in this paper. This phenomenon can be applied for the improvement of the recovery peculiarity of the optical stopping effect by means of the increase of the added assistant pump light.