Moshe Zohar

Novel resonant cavity-enhanced absorber structures for high-efficiency midinfrared photodetector application

AnewdielectricFabry-Perotcavityisconsideredforenhancedopticalabsorptionina thin semiconductor layer embedded within the resonant cavity. In this design, the front (furthest from the illuminated side) mirror is a grating structure with nearly perfect retroreflection. Proof of concept, including semianalytical calculation, and computer-aided design and simulation is performedforapplicationinamidinfraredwavelengthbandbasedonaHgCdTeabsorbinglayer. The results indicate that this new type of cavity meets the combined challenges of significantly increasing the absorption efficiency and reducing the overall complexity and size of the entire device, in comparison to a conventional resonant cavity, in which both mirrors are formed from quarter-wavelength multilayer stacks. C 2011 Society of Photo-Optical Instrumentation Engineers

Resonance cavity enhanced midinfrared photodetectors employing subwavelength grating

A new type of resonance cavity enhanced (RCE) photodetector is being proposed. The cavity in this structure includes a grating with nearly perfect retro-reflection as a front mirror and conventional multilayer structure as the back mirror.

Solar cell efficiency improvement using dip-pen nanolithography

Abstract. An innovative approach to improve the performance of photovoltaic solar cells is presented. Until recently, the fabrication of grating layers has been well proven using bulk micromachining techniques, but lately low-cost dip-pen nanolithography (DPN) has been proposed as a method for printing nanostructures on different substrates and has matured to become one of the most versatile patterning techniques available at the nanoscale. However, this technique has scarcely been studied and tested for fabricating grating layers. In this research, submicron grating patterns from high refractive index polymers are fabricated on a few types of solar cells, significantly improving their efficiency. The appropriate geometries and materials for the grating patterns are obtained via numerical optimization using rigorous coupled wave analysis for electromagnetic simulations of the grating multilayer. Possible light-confinement schemes are analyzed, and their figures of merit are assessed. The simulation of the electrical characteristics is integrated with postdesign electromagnetic simulation. The corresponding theoretical and experimental studies shed light on the impact of the merger of the grating structure with the light harvester on the device’s optical and electrical properties. Success in using DPN paves pathways to low-cost fabrication of light harvesting devices with improved performance.

High sensitivity photodetectors based on nanometer scaled periodic multilayered structures

We propose and design high efficiency thin Photodetectors (PDs), using micro-cell gratings, which enable near-field enhanced (NFE) mid IR absorption by confining the EM fields to the absorber region. These PD types have a different operation principle as compared to the conventional PDs they replace.

Grating Mirror Based High Efficiency Optical Resonance Cavity: Application to IR Photodetectors

In this work the concept of merging diffraction grating as a mirror into optical resonance cavity is proposed and proved by rigorous simulations on example of mercury cadmium telluride resonance cavity enhanced IR photodetector.