Development of an optical storage system of semiconductor nanocxystal thin film

研究了纳米半导体光存储的原理和机理，开发了光存储介质。并对其制备工艺进行了研究。我们的前期工作已经发现，由半导体纳米粒子组成的薄膜的光致发光强度随着紫外光照射时间的增加而增加。控制光致发光强度的唯一途径是控制照射周期。因此，光存储器的应用受到了限制。我们发现，光致发光的增加比例可以通过照射光的强度来控制。弱光比强光更能提高增加比。结果表明，通过控制辐照光的强度，可以实现多值记录。由于光致发光的增加是可逆的，所以多值记录是可重写的。结果表明，该介质比现有的双值介质密度更高，可产生更多的0和1之类的可重写介质。多值记录及其读数可以通过单波光完成。因此，期望通过使用相同的光学头进行写入和擦除来实现简单的读取装置。为了制备大面积、高速涂覆的纳米颗粒薄膜，必须开发一种湿法工艺。微粒上的表面力和布朗力对较小的微粒起主导作用。然而，这些对粒子自排序的影响在实验上还没有得到很好的理解。考虑颗粒间通过液体表面的相互作用力，对干燥过程中的颗粒进行了自排序。然后我们意识到自有序可以分为三种模式：(1)晶体，如六边形或四边形有序，(2)随机聚集，(3)分散晶体，如结肠晶体。特别是，从我们的模型中得到的有序状态表明，我们可以用湿法制备高度有序的薄膜。该方法不仅可以应用于半导体纳米颗粒薄膜的制备，而且可以应用于其他广泛的技术领域。少

The principle and the mechanism of the optical memory using semiconductor nanoparticles are studied for developing an optical memory media. The fabrication process is also studied. It was already discovered by our previous works that the intensity of photoluminescence of thin films consisting of semiconductor nanoparticles increases with irradiating time of UV light. The only way to control the intensity of photoluminescence was the irradiating period. Therefore, the application of an optical memory was limited.We discovered that the increase ratio of the photoluminescence can be controlled by the intensity of irradiating light. The weak light can enhance the increase ratio more than the strong light. This result shows the possibility of multi-value recordings by controlling the intensity of irradiating light. Since the increase of photoluminescence is reversible, the multi-value recording is rewritable. It is concluded that higher density rewritable media than current double- value re … More cording such as 0 and 1 can be produced. The multi-value recordings and their reading can be done by a single wave of light. Therefore, a simple reading device is expected by employing a same optical head to both write and erase.A wet process must be developed in order to fabricate thin films of nanoparticles for large area and with high speed coating. The surface force on a particle and the Brownian force become dominant for smaller particles. However, those effects on the self-ordering of particles are not well understood experimentally. We have carried out the particle self-ordering during drying with considering the interaction forces among particles through the liquid surface. Then we realized that the self-ordering can be categorized to three patterns : (1) crystals such as hexagonal or tetragonal ordering, (2) random aggregates, and (3) dispersed crystals like a colonic crystal. Especially, the ordering state obtained from our model suggests that we can fabricate the thin films highly ordered by wet processes. This method can be applied to not only the fabrication of thin films of semiconductor nanoparticles but also other broad technology area. Less