SPIE Prague - University of Minnesota Fabricating 1 nm insulator gaps by ALD

SPIE Optics + Optoelectronics began in Prague on 13 April and continues through 16 April at the Clarion Congress Hotel had an intersting plenary on ALD showing how ALD is used to fabricate high aspect ratio metal-insulator-metal structures with insulator gaps as small as 1 nanometer, as reported by SPIE News room:

 

 

Ferenc Krausz and Sang-Hyun Oh between talks at the plenary session.

Fabricating through atomic layer deposition: Sang-Hyn Oh plenary

Precise layer-by-layer deposition of dense, conformal metal oxide films through atomic layer deposition (ALD) methods enables the fabrication of structures providing unique plasmonic and optoelectronic characteristics. Sang-Hyun Oh of the University of Minnesota described the use of ALD in his lab to fabricate high aspect ratio metal-insulator-metal structures with insulator gaps as small as 1 nanometer. The work presented highlighted the value of ALD in providing precise control of device performance and the variety of applications that can benefit from using the technique.

In particular, applying these techniques to create annular gap structures allows for varying plasmon resonance wavelength with gap dimension as well as varying transmission through the structure. Such control could be useful in nonlinear optics, biosensing, optical trapping, and spectroscopic applications.

Varying ring size and coupling the structures with graphene results in performance which could be of interest in optoelectronic devices. The dynamic light control demonstrated by combining these nanometer-sized gaps with two dimensional materials also has applications in mid-IR and Raman spectroscopy, and the use of these "nanogaps" as nano-electrodes in dielectrophoresis to trap molecules was demonstrated.

A final demonstration of the utility of ALD made use of silicon, which after a KOH etch can be used as a template for the ALD process, to form ultrasharp probes for scanning probe microscopy.