Research On Nanosilicon Light Emitting Diodes

Nowadays, the research on light emitting materials based on nanosilicon has been the hot area of the world concern. It not only has significant impact on the microelectronics industry, but also has great significance to achieve the establishment of optical interconnection and the realization of quantum compute.It has a lot of means to prepare light emitting materials base on silicon, while the method of pulsed laser etching(PLE) and pulse laser deposition(PLD) of compound preparation and processing system is used in our experimental group to prepare silicon quantum dots, quantum wire and nanostructure films. Using the method of pulsed laser etching(PLE), the atom on the surface of the target is bombarded out, besides the plasma is produced by high voltage and the plasma is deposited on the substrate by pulsed laser deposition(PLD). Gas or solid atom as Oxygen, Nitrogen and ytterbium are doped in the nanosilicon. By using high voltage, plasma deposits on the substrate under the action of the electric field, and makes the ionized gas plasma and target materials deposits on the surface of the substrate at the same time, which destroys the periodic structure of the surface at the same time. Solid doping by pulsed laser direct effect generated in the target environment with high temperature and high pressure plasma deposition on the substrate. Doping or nanostructure of silicon could both impact the band structure, and regulate the band structure through quantum confinement effect and curved surface effect. The original indirect band gap is transformed into a quasi direct band gap structure, which greatly improves the luminous efficiency.The position of the local states in the band gap can be influenced by the different gas atmosphere or different doping conditions, and it will affect the wavelength of light emission. Species of doped gas, concentration and micro regulation of doping ratio will influence the position of localized states. Therefore, we could regulate and control the atmosphere accurately to regulate the local states and the wavelength of emission, which has important significance and broad application prospects for the study of the luminescence of nanosilicon.In addition to the different gas atmosphere, gas pressure will also affect the emission wavelength, and the annealing temperature is also one of the important factors affecting the activation of nanosilicon. When the temperature is higher, the intensity of the peak of the photoluminescence spectrum will decrease, and the peak will have a red shift phenomenon. At lower temperature, the electrons in the conduction band are captured in the local states in the band gap, then the electrons in the local states near the conduction band and the holes in the local states near the valence band can format the inversion state of particles. This can lead to the enhancement of photoluminescence and even the stimulated emission. At higher temperatures, however, more and more electrons are excited from localized states to the conduction band. The excited electrons band and the holes in the valence formed a weak blue shift photoluminescence spectrum by the combination. Therefore, the local state luminescence can be destroyed at higher temperature.We also test nanocrystalline silicon device, and found that the threshold value of the luminescence spectrum is between 5V-7V. Besides with the increase of the pump voltage, the intensity of the light emission increases, and with the increase of the voltage, we can clearly observe that the curve of the electroluminescence has a tendency to increase with the increase of the super linear. After calculating we get the quantum effect of the external quantum effect can reach more than 10%. The peak is produced by silicon quantum dots doped by ytterbium, which is part of emission of quantum dots.