Preparation And Properties Of Heat Evaporation Mg₂Si/Si Heterojunction

Magnesium silicide?Mg₂Si? which is environmental friendly and a kind of narrowband-gap indirect semiconductor materials. At present, the microelectronics industry is mainly based on silicon?Si?. Growing Mg₂ Si thin films on a Si substrate, can be well compatible with Silicon technology, so the Mg₂Si/Si heterojunction structure is of great value in research.In this paper, the environmental friendly Mg₂ Si thin films are prepared by resistive thermal evaporation on n-Si and p-Si substrate, so the effects of the thickness of Mg film evaporated on the quality of Mg₂ Si thin film are investigated. On the basis of this, the technology of the preparation of the Mg₂ Si heterostructure is studied, and the electrical and optical properties of Mg₂ Si thin films are studied.First of all, the Si and Mg films are deposited on the Si substrate by resistive thermal evaporation at room temperature, and then after the heat treatment process in a low vacuum?10-1Pa-10-2Pa? atmosphere, the Mg₂ Si thin films are prepared. 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. And the effects of the thickness of Mg on the growth of Mg₂ Si are studied, the results showed that Mg films showed a good crystallinityand flatness, when the thickness are at 370 nm.Secondly, the preparation of the Mg₂ Si heterojunction is studied. Mg₂Si/n-Si, Mg₂Si/p-Si heterojunction devices were prepared on Si substrates, then, the electrical properties and optical properties of the Mg₂Si/n-Si and Mg₂Si/p-Si heterojunction are investigated by four probe testing systems, semiconductor properties analyzer, spectral response measurement system and other equipment. The results show that the resistivity of Mg₂ Si thin films to increase then decreased with the increase of the thickness of Mg; Mg₂ Si / n-Si heterojunction than Mg₂ Si / p-Si heterojunction exhibit more ideal PN junction electrical properties; Mg₂ Si / n-Si heterojunction in the infrared light spectrum showed a strong response.Finally, the preparation of Si / Mg₂ Si / Si double heterostructure on n-Si substrate p-Si / Mg₂ Si / n-Si double heterostructure device fabricated using semiconductor characterization analyzer, spectral response measurement system and other equipment of p-Si / Mg₂ Si / n-Si double heterostructure conduct electrical and optical properties of. The results showed that: p-Si / Mg₂ Si / n-Si double heterostructure showed the same unidirectional conductivity, and p-Si / Mg₂ Si / n-Si double heterostructure has a ratio Mg₂ Si / n-Si heterojunction lower forward voltage and higher resistance to breakdown voltage. In infrared light, p-Si / Mg₂ Si / n-Si double heterostructure exhibited and Mg₂ Si / n-Si heterojunction very similar spectral response capability in the ultraviolet and visible light, p-Si / Mg₂ Si / n- Si double heterostructure spectral response is much stronger than Mg₂ Si / n-Si heterojunction.