The Preparation And The Design Of The Magnesium Silicide Film Sensor

The preparation of Mg2 Si film by magnetron sputtering technique has been investigated mainly. The effects of the thickness of on the growth of Mg2 Si and the relationship between the thickness of Mg film and the prepared Mg2 Si film after annealing and electrical and optical properties of Mg2 Si heterojunction for optical sensor are studied.This thesis includes seven chapters. In Chapter 1,the research background and the meaning of the topic were introduced. The short introductions to the procedure and methods for preparing Mg2 Si films were given, and the working principles of the equipments used to prepare and characterize Mg2 Si films were presented in Chapter 2.Chapter 2.Chapter 3-6 are the important parts of this thesis.The basic properties of Mg2 Si heterojunction prepared by magnetron sputtering technique, the effects of the thickness of on the growth of Mg2 Si and the relationship between the thickness Mg film and the prepared Mg2 Si film after annealing are studied in Chapter 3. The XRD and SEM results showed that the single-phase Mg2 Si films are prepared successfully after 4 hour’s annealing, with compact, homogeneous and continuous grains, smooth surface and good crystallinity. The thickness of Mg2 Si films increases with the increase of the thickness of Mg films.The thickness of Mg2 Si films is about 0.9-1.1 times to that of Mg films.In Chapter 4, four probe testing system, semiconductor properties analyzer, the spectrophotometer and other equipments were used to get the electrical and optical properties of the Mg2Si/Si heterojunction. The results show that the resistivity of Mg2Si/Si heterojunction decreases with the increase of the thickness of Mg2 Si. The Mg2Si/Si heterojunction showed unidirectional conduction property. The infrared light was absorbed by the Mg2Si/Si heterojunction 20% more than the silicon substrate. A obvious rising of the absorption rate of Mg2Si/Si heterojunction was noticed at the wavelength between 1200 nm and 1350 nm.Optical properties were studied with the reflection spectrum of and Kramers-Kroning(K-K) relation in Chapter 5. It was showed that the band gap of the film was 0.918 eV and in the infrared region, the absorption coefficient between the band gap of silicon and Mg2 Si was 104cm-1 more than other areas.In Chapter 6, the electrical and optical properties of the Si/Mg2Si/Si heterojunction was studied briefly. The results show that the resistivity of Mg2Si/Si heterojunction increases with the increase of the thickness of Mg2 Si. The Si/Mg2Si/Si heterojunction showed unidirectional conduction property and the turn-on voltage of Si/Mg2Si/Si heterojunction structure is relatively large. The interference phenomenon was found in the reflection spectrum of Si/Mg2Si/Si heterojunction.