Quantum‐Tunneling Metal‐Insulator‐Metal Diodes Made by Rapid Atmospheric Pressure Chemical Vapor Deposition

Abstract

A quantum-tunneling metal-insulator-metal (MIM) diode is fabricated by atmospheric pressure chemical vapor deposition (AP-CVD) for the first time. This scalable method is used to produce MIM diodes with high-quality, pinhole-free Al 2 O 3 films more rapidly than by conventional vacuum-based approaches. This work demonstrates that clean room fabrication is not a prerequisite for quantum-enabled devices. In fact, the MIM diodes fabricated by AP-CVD show a lower effective barrier height (2.20 eV) at the electrodeinsulator interface than those fabricated by conventional plasma-enhanced atomic layer deposition (2.80 eV), resulting in a lower turn on voltage of 1.4 V, lower zero-bias resistance, and better asymmetry of 107.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/adfm.201805533. dielectric layer sandwiched between two metal contacts. MIM diodes are capable of rectification in the high frequency range due to a femtosecond quantum-tunneling electron transport mechanism through the insulator, making them attractive for applications in solar rectennas, [1] infrared detectors, [2,3] and wireless power transmission. [4] However, the insulator layer in the MIM stack, which plays a crucial role in determining the diode performance, [5] is typically deposited using vacuum-based methods, such as sputtering, [6] anodic oxidation of sputtered films, [7] electron beam deposition, [8] and especially atomic layer deposition (ALD), [9] which is commonly used due to its ability to deposit nanoscale films with high accuracy and uniformity. High-throughput fabrication of MIM diodes is limited by slow deposition rates and the need for a vacuum environment. Scalable techniques are therefore needed for depositing nanoscale films for the next generation of integrated quantum devices. Some deposition processes have been introduced to fabricate thin films at atmospheric pressure for nanoelectronic devices that utilize quantum phenomena. Thermal and anodic oxidation, for example, have been used to grow thin CrO x and Nb 2 O 5 films on Cr and Nb layers for MIM diodes [7,10] ; atmospheric pressure metal organic vapor phase epitaxial growth (AP-MOVPE), or atmospheric pressure metal organic chemical vapor deposition (AP-MOCVD), has been used to fabricate InGaAsP multiquantum-well structures for optical devices [11] ; the Langmuir Blodgett technique was used to deposit a ZnO film for a MIM diode [12] ; and a chemical vapor deposition (CVD) furnace operated at atmospheric pressure has been used to deposit a TiO 2 film in a tunneling transistor. [13] The need for high temperatures, specific metal films for oxidation, and complex compound precursors in these techniques, as well as challenges in reproducibility, highlight the need for new methods to reliably deposit enabling films for cost-effective quantum devices. Recently, atmospheric pressure spatial atomic layer deposition (AP-SALD) systems have been utilized to grow uniform films for different applications including solar cells...

In-situ observation of nucleation and property evolution in films grown with an atmospheric pressure spatial atomic layer deposition system

“…The trend of increasing Al 2 O 3 refractive index as a function of deposition temperature was similar to that of films grown by conventional ALD. An ex situ characterization technique such as x-ray photoelectron spectroscopy [10] or ion beam analysis [74,75] is warranted to study variation in the film's chemical composition and its effect on the optical properties.…”

“…Growing interest in spatial ALD has led to several review papers in recent years [3][4][5][6], and companies such as Levitech, Beneq, and SoLayTec have commercialized spatial ALD systems. Both metal oxides and metals have been deposited [4,5,7], and AP-SALD and AP-CVD films have been utilized in thin film transistors [8,9], metal-insulator-metal diodes [10], photovoltaic devices [2,[11][12][13][14][15][16][17], and LEDs [18][19][20]. Yet despite the promise of these techniques, little has been done to characterize the nucleation and property evolution of these nanoscale films.…”

Ultrathin TiOx Interface‐Mediated ZnO‐Nanowire Memristive Devices Emulating Synaptic Behaviors

“…In contrast, the ZnO nanowire devices with these interfacial layer demonstrated similar current response as that in the TiO x interfacial layer (Figure S11b,d, Supporting Information). As the deposited ZnO and Al 2 O 3 layer are rich in defects in nature from our previous studies, these defects are expected to play a similar role as distributed trap states for electron hopping and assisting electron tunneling at low and high electric field, respectively.…”

An Optically Responsive Soft Etalon Based on Ultrathin Cellulose Hydrogels

“…These are well established optical structures and are used in lasing applications, as light absorbers, and as etalons . MIM structures usually comprise thin‐film stacks of rigid materials with semiconductor alloys, metallic oxides, or metal nitrides as the insulating layer. More recently, soft materials including liquids, polysiloxane, PDMS, silk protein, and polyimide, have also been used as the insulating layer, in order to introduce flexibility.…”