Study of Tunneling Switching Operation in Various Tunneling Barrier Materials

There has been increasing demand for electronic devices with ultra-high working frequency or speed to process big data quickly, especially in the fields of communications, the military, and aerospace as well as a high performance control process unit (CPU). However, traditional semiconductor switching devices cannot keep up with the demands of increased speed. Typical semiconductor switching devices are generally used a p-n junction and a Schottky barrier which perform a switching operation by combining electron and holes. A short channel length between source and drain is only solution to achieve high speed. It faces limit due to the resolution limit of the fabrication process and the short channel effect. Electron mobility was considered instead of physical dimension. Although high electron mobility transistor (HEMT), based on III-V group materials, is expected to increase the speed, its theoretical frequency limit is less than 1THz, even with several nanometer channel lengths. Thus, we have to solve the problem of switching speed through a new method.<br/>Tunneling phenomenon is key mechanism as fast switching devices due to direct movement of electrons without hole-electron combination. Although tunneling mechanism can provide ultra-high working speeds (&gt;THz), the very low switching ratio results in poor switching efficiency. Improving switching efficiency is highly motivated for high-speed efficient switching elements.<br/>Our strategy is geometric electrode design to increase switching efficiency (On-off ratio). We have already demonstrated the effectiveness of geometric design. We also study various tunneling barriers to maximize it and the phenomenon (Tunneling transition between direct and Fowler-Nordhiem tunneling).