NSTOA-13-RA-108 Comparison of the Effects of Varying of Metal Electrode in Metal-Insulator-Metal Diodes with multi-dielectric layers

Research Article

Austin J Nanomed Nanotechnol. 2014;2(2): 1014.

NSTOA-13-RA-108 Comparison of the Effects of Varying of Metal Electrode in Metal-Insulator-Metal Diodes with multi-dielectric layers

M. Alhazmi F1, Aydinoglu B. Cui1, O. M. Ramahi2, M. Irannejad1,2, A.Brzezinski1 and M. Yavuz1,*

1Waterloo Institute for Nanotechnology (WIN), University of Waterloo, Canada

2Electrical and Computer Engineering, University of Waterloo,Canada

*Corresponding author: M. Yavuz, Department of Mechanical and Mechatronics Engineering and Waterloo Institute for Nanotechnology University of Waterloo, Canada

Received: December 04, 2013; Accepted: January 24, 2014; Published: January 28, 2014


Different metal–insulator–metal diodes using the fixedbottom electrode with different top electrodesandmulti–insulator layers were investigated. Chromium was usedfor the bottom metal electrode andTi, Cr, Al, and Pt were used asthe top metal electrode. The effects of tunneling junction and its effects in the diode performance were also studied. The high asymmetry value of 40, 16 and 6 were obtainedon applied voltage in the range of 0.5–3V respectively on using the Ti, Cr and Pt as the second metal electrode in the Metal–4 insulator layers–Metal diodes, while a combination of Cr–insulator layers–Al was shown relatively weak asymmetry curve.


The demand for using a sufficient and clean source of energy is continuously increased. Therefore, investigation of a fast response time rectifying element is essential to overcome the issue of having insufficient rectification [1]. The best candidate rectifying diode is metal–insulator–metal (MIM) diode due to its advantages over semiconductor solar cells in terms of response time [2]. MIM diode is defined as a junction consisting of thin insulating layer (i.e. less than 10nm) between two metal electrodes [3,4]. Eventhough the architecture of this type of diode is simple; finding most suitable materials for producing high electrical performance is still a challenge. In addition to the insulator materials, there are some other important parameters such as current–voltage (I–V), nonlinearity, and asymmetry curves which affect the diode's performance. It is impossible to achieve both high asymmetry and nonlinearity by using MIM diodes with single insulator layer [5], and it has been reported that metal–double insulator–metal (MIIM) diodes can overcome this concern5. The insulator physical and chemical material properties such as work function [1],φ, electron affinity, χ, junction area, thickness and number of layers and their orders are the most important parameters that determine the MIM diode performance. The I–V curve strongly depends on the barrier height between the insulator and electrode and order of insulator. The potential barrier between the base electrode and the first insulator determines the turn on voltage, however, the potential barrier between the last insulator and top electrode determines the breakdown voltage according to the side of applied voltage.

Recently, P. Maraghechi et.al [6] studied the MIM diode structure with three insulator layers of Cr2O3–HfO2–Al2O3with different order. It was reported that the Cr/Cr2O3–HfO2–Al2O3/Cr diode exhibited a cascaded potential barrier profile; however non–cascaded profile wereobserved for the case of Cr/Cr2O3–Al2O3–HfO2/Cr diode. The former diode exhibited large degrees of asymmetry of (104) and nonlinearity (x=6).

Here, four different MIM diodes with multi–layers of insulators (i.e. four dielectric layers) by changing the top metal electrodes and keeping the bottom one fixed were studied. The I–V characteristics curve and asymmetrical, non–linearity curves of the fabricated diodes with different top electrode of Ti, Cr, Al, and Pt were also investigated.

Experimentand methodology

It is known that the insulator thickness changes the electron tunneling efficiency [1]. The tunneling process in the insulator layer is occurred at thickness of <10 nm. However, insulator thickness less than 4 nm is essential for achieving efficient tunneling. Therefore,in this study we were kept the total thickness insulator layers of all fabricated MIM devices as 3 nm to achieving high probability of the tunneling. A series of MIM diodes were fabricated on the SiO2 substrate to avoidthe conductivity of the substrate during the electrical characterization. In MIM fabrication, the first metal (bottom) electrode and insulator layers were fixed while different metals were used as the second metal (top) electrode as listed in table 1.