Abstract
Thin film metal–insulator–metal (MIM) diodes have attracted significant attention for use in infrared energy harvesting and detection applications. As demonstrated over the past decades, MIM or metal-insulator-insulator-metal (MIIM) diodes can operate at the THz frequencies range by quantum tunneling of electrons. The aim of this work is to synthesize required ultra-thin insulating layers and fabricate MIM diodes using the Langmuir-Blodgett (LB) technique. The nickel stearate (NiSt) LB precursor film was deposited on glass, silicon (Si), ITO glass and gold coated silicon substrates. The photodesorption (UV exposure) and the thermodesorption (annealing at 100 °C and 350 °C) methods were used to remove organic components from the NiSt LB film and to achieve a uniform homogenous nickel oxide (NiO) film. These ultrathin NiO films were characterized by EDS, AFM, FTIR and cyclic voltammetry methods, respectively. The MIM diode was fabricated by depositing nickel (Ni) on the NiO film, all on a gold (Au) plated silicon (Si) substrate. The current (I)-voltage (V) characteristics of the fabricated diode were studied to understand the conduction mechanism assumed to be tunneling of electron through the ultra-thin insulating layer. The sensitivity of the diode was measured to be as high as 35 V-1. The diode resistance was ∼100 ohms (at a bias voltage of 0.60 V), and the rectification ratio was about 22 (for a signal voltage of ±200 mV). At the bias point, the diode response demonstrated significant non-linearity and high asymmetry, which are very desirable characteristics for applications in infrared detection and harvesting.
Highlights
High-frequency diode rectifiers are very important for applications such as IR sensing,[1,2,3,4,5] solar energy harvesting,[6,7,8,9,10,11] THz electronics,[12] THz mixing[13] and display technologies.[14]
A MIM diode, which is an ultra-thin insulator layer sandwiched between two metal electrodes, is a better rectifier compared to a Schottky diode beyond ∼12 THz.[27,28]
A Rectenna, antenna coupled with a MIM diode, could be used as an IR detector or thermal energy harvester by a suitable choice of an antenna and a quantum tunneling MIM diode
Summary
High-frequency diode rectifiers are very important for applications such as IR sensing,[1,2,3,4,5] solar energy harvesting,[6,7,8,9,10,11] THz electronics,[12] THz mixing[13] and display technologies.[14] MIM/MIIM diodes are vigorously studied as high-frequency rectifiers[1,3,15,16,17,18,19,20,21] for various applications. Because of its high frequency response, the Schottky diode is widely used as a rectifier, Schottky diodes cannot operate efficiently at THz frequencies. A MIM diode, which is an ultra-thin insulator layer sandwiched between two metal electrodes, is a better rectifier compared to a Schottky diode beyond ∼12 THz.[27,28] A potential barrier is formed between the Fermi level of the metal electrode and the conduction band of the insulator. Time constants in the femto-second (10 15 s)[30] range make the quantum-based
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