有機雙穩態記憶體之製作與特性分析

Abstract

在本篇論文當中，我們成功製作出以有機材料為主的雙穩態記憶體元件。主要的結構類似三明治架構，在兩個金屬電極中，嵌入一層有機半導體層。此結構在低電壓驅動下，它處在高電阻狀態，也就是低導電性狀態；當持續增加電壓大於臨界電壓時，電流會大幅提升而進入高導電性狀態。因此，此元件擁有兩種狀態，而我們定義它為”0” 和”1”。此元件之物理機制我們推測是藉由上電極與有機材料的蕭基接面及界面陷阱所造成的。

在之後的篇章中，我們又更進一步的簡化我們的元件結構，省去下電極的製程，而形成N 型參雜基板/有機材料/鋁的簡單結構。此元件的製程，只需要簡單的兩道蒸鍍製程，大幅減去製程時間。另一方面，我們也探討有機材料的鍍率差異對元件電性的表現有何影響，我們發現元件的臨界電壓會隨著有機材料的表面粗糙度愈大而變大，同時， 此結構在基板與有機材料之間有一極化現象，我們推測此現象會造成元件的臨界電壓變大，以及造成元件的穩定度較差。

We have fabricated an electrical bistable device with a simple structure, an organic layer interposed between the Al electrodes. A bistable device is an electronic device with two conductivities at the same applied voltage. That is, at writing bias scan, the device holds at high resistance state at the beginning. It will switch into high conductance state as the sweeping voltage pass threshold voltage. After applying reading bias, the device still holds at high conductance state. Therefore, this device exhibits two distinctly different currents at the same applied voltage. The formation of the bistable states is probably caused by electron trapping by the defects at the Schottky junction under electrical field stressing.

Later, we investigate another bistable device with Al/Alq3/n-type Si structure. It contains a heterostructure, and only two-layer deposition is needed in this structure. Current-voltage characteristic is similar to that of metal/organic semiconductor/metal structure, the three-layer structure widely used for organic memory devices, is obtained. Moreover, we are able to modify the electrical properties by utilizing appropriate deposition rates and thickness. This device shows extremely simple fabrication process and great potential in future advanced organic flexible display.