Development of an optical storage system of semiconductor nanocxystal thin film

为了研制光存储介质，研究了半导体纳米粒子光存储的原理和机理。并对制作工艺进行了研究。我们在前期的工作中已经发现，半导体纳米颗粒组成的薄膜的光致发光强度随紫外光照射时间的增加而增加。控制光致发光强度的唯一方法是照射时间。我们发现光致发光的增长率可以通过照射光的强度来控制。弱光比强光能更大程度地提高增长率。这一结果显示了通过控制照射光的强度进行多值记录的可能性。由于光致发光的增加是可逆的，因此多值记录是不可逆的。得出了比目前的双值介质密度更高的介质 ...更多信息 可以产生诸如0和1的编码。多值记录和它们的阅读可以通过单个光波来完成。因此，需要一种简单的阅读装置，即用同一个光学头进行写入和擦除。颗粒上的表面力和布朗力对于较小的颗粒变得占主导地位。然而，这些对粒子自序的影响在实验上还没有得到很好的理解。在考虑颗粒间通过液面的相互作用力的情况下，研究了干燥过程中颗粒的自有序性。然后我们意识到，自有序可以分为三种模式：（1）晶体，如六方或四方有序，（2）随机聚集体，和（3）分散晶体，如结肠晶体。特别是，从我们的模型得到的有序状态表明，我们可以通过湿法工艺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