Metal-Insulator-Metal tunnel diode with various materials and structural designs for rectifying effect

Abstract

Electrical characteristics of metal-insulator-metal (MIM) tunnel diodes with various materials and structural designs for high speed operation and rectification effects have been studied. Recently, high speed devices have been demanded in many fields such as high performance control process unit (CPU), optoelectric devices and communications. Among various electrical components for high speed working, in here, rectifying diodes have been studied as basic building block structure for the high-speed devices.Traditionally, PN junction diodes and Schottky diodes have been studied intensively for rectifying function. However, the mechanism of the pn junction diode is not suitable for high speed rectification due to the large depletion region width. For Schottky barrier diode, it is more suitable for high-speed switching. Since it has very short reverse recovery time. However, the driving frequency limit of Schottky diode is around 5THz. Therefore, new rectifying mechanism operating at a high frequency should be suggested. As one of the rectifying diode, MIM diode is operated by quantum electron tunneling effect which occurs when a particle passes through a thin potential barrier. So, MIM tunnel diode is enabled high-speed switching and it can have a low operating voltage. In order to increase the high-speed operation and rectification effect of MIM diode structure, the MIM diode should have a thin insulator layer as a tunneling barrier. Moreover, the current-voltage characteristics of the devices should have non-linearity and asymmetry. However, due to the tunneling mechanism of device structure, the non-linearity or asymmetry characteristics should be improved. Therefore, this paper was focused to improve the non-linearity and asymmetry characteristics of MIM diode. To improve the non-linearity and asymmetry characteristics of the diode, the various MIM diode structure were studied different work function of metal, double insulator layers and device design as important parameters. The simple flat MIM didoes, metal-insulator-insulator-metal (MIIM) diode, and vertical metal cylinder structure (VMCS) MIM diode have been studied. The simple flat MIM diode considering material effect together did not show high non-linearity and asymmetric characteristics. However, the flat MIIM diode has good non-linearity and some asymmetry in there I-V characteristics. Although VMCS MIM diode did not have a better non-linearity and asymmetry properties. However, the VMCS MIM diode shows the non-linearity and asymmetry characteristic more improved than simple flat MIM tunnel diode. Therefore, we could show the feasibility of high speed switching and rectification in MIM diode using the vertical metal cylinder structure which is applied the device design as a parameter. These new MIM diode structure can be applied to various field such as new electronic devices, rectifier antennas for energy harvesting, optical devices, infrared/terahertz detectors in high frequency range, and electric high-speed switching devices. ⓒ 2017 DGIST