The Preparation Of Magnesium Silicon Materials And Design Of LED Devices

Magnesium silicide(Mg2Si), which is environmental friendly, is a kind of narrow- band-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 magnetron sputtering on Si substrate and insulating substrate, so the effects of the thickness of Mg film sputtered on the quality of Mg2 Si thin film are investigated. On the basis of this, the technology of the preparation of the LED devices with 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 and the insulating glass substrate respectively by magnetron sputtering 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.Secondly, the effects of the thickness of on the growth of Mg2 Si and the relationship between the thickness of Mg film and the formatted Mg2 Si film after annealing are studied. The results show that, Mg films showed a good crystallinity and flatness, when the thickness are at 2.52 μm, 2.72 μm. The thickness of the Mg2 Si films increased with the increasing of the thickness of Mg films, which is about0.9-1.1 times of that of Mg films. The research will play an important role in guiding to design the devices based on Mg2 Si film.Finally, the preparation of the light emitting device based on Mg2 Siheterojunction is studied. Mg2Si/Si, Si/Mg2Si/Si heterojunction LED devices were prepared on Si substrates, then,the electrical properties and optical properties of the Mg2Si/Si and Si/Mg2Si/Si heterojunction are investigated by four probe testing systems, semiconductor properties analyzer, steady-state / transient fluorescence spectrometer and other equipment. The results show that the resistivity and the sheet resistance of Mg2 Si thin films decreases with the increase of the thickness of Mg2Si;Mg2Si/Si, Si/Mg2Si/Si heterojunction showed good single guide better pass characteristic, and the Si/Mg2Si/Si double heterojunction structure turn-on voltage is relatively large, which is about 3V; the photoluminescence intensity of Mg2Si/n-Si heterostructure devices is maximum at the wavelength of 1346 nm. the photo-luminescence intensity of the Mg2 Si thin films prepared on an insulating substrate also shows the Maximum.Comparison the photoluminescence of Mg2 Si thin films on different substrates, the Mg2 Si were prepared on the high purity quartz substrate shows that the luminous characteristics of infrared monochromatic.