In disordered media light can be localized in the spaces between scattering sites which average to an optical mean free path (MFP). However the fundamental question of the smallest MFP that can support Anderson localization of light remains unanswered due to fabrication complexity of a scattering medium with controlled nano-scale gaps and lack of required resolution by far-field methods. Here we use scanning probe microscopy technique to collect localized light created at gaps between scattering crystallographic defects in a large variety set of nano-gap III-V medium. No localized spots correlated to MFP below ~14.5 nm is observed at second-harmonic collection at 390 nm. Experiment and simulation resulted in the first direct observation of suppression of Anderson light localization correlated to ~13 nm optical MFP that reveals a fundamental constraint in electromagnetism and photonics.
Heteroepitaxial crystalline films underlie many electronic and optical technologies but are prone to forming defects at their heterointerfaces. Atomic‐scale defects such as threading dislocations that propagate into a film impede the flow of charge carriers and light degrading electrical/optical performance of devices. Diagnosis of subsurface defects traditionally requires time‐consuming invasive techniques such as cross‐sectional transmission electron microscopy. Using III–V films grown on Si, noninvasive, bench‐top diagnosis of subsurface defects have been demonstrated by optical second‐harmonic scanning probe microscope. A high‐contrast pattern is observed of subwavelength “hot spots” caused by scattering and localization of fundamental light by defect scattering sites. Size of these observed hotspots are strongly correlated to the density of dislocation defects. The results not only demonstrate a global and versatile method for diagnosing subsurface scattering sites but uniquely elucidate optical properties of disordered media. An extension to third harmonics would enable irregularities detection in non‐χ (2) materials making the technique universally applicable.
This paper reports recent efforts of the intersectoral iNEMI consortium towards bridging the traceability gap in the characterisation of dielectric materials used in 5G applications. Several GHz resonators, in SCR, SPDR, and FPOR topologies are applied to four samples fabricated from the same COP coupon. Characterisation is performed at three laboratories, using VNAs of different form-factors, and covering the frequency range of 10–110GHz. Excellent agreement is demonstrated between the methods and the samples. Consistent measurements at 10 GHz provide a trace to more conventional material measurements in the microwave range.
Ongoing research at SUNY Polytechnic Institute to enable large scale fabrication of quantum devices with tightly controlled performance characteristics will be presented. Josephson junctions and transmon qubits patterned with 193 nm lithography will be used to illustrate how advanced process tools can control critical dimensions of devices, necessary for building larger ensembles of qubits. Advances in the CMOS industry enable superior surface roughness and interface quality to be achieved across the entire 300mm wafer – some examples will be presented. The integration of photonic circuits (waveguides and on-chip cryogenic IR emitters) with superconducting Josephson junctions to enable large-scale neuromorphic computing structures in the near future will be discussed. Ongoing work on developing materials and processes for UV-transparent photonic circuits at 300mm will be presented – such chips could be useful as part of the interface to trapped ion qubits. The talk will wrap up with a discussion of the synergies in technology development, and functionality integration that can be achieved using an advanced fabrication facility.
The measurement of the sheet resistance of Arsenic implanted layers is almost exclusively used for the monitoring of temperature nonuniformity of RTP equipment. However, as is shown in this contribution this technique relies on several averaging processes and a satisfactory uniformity of sheet resistance achieved on the implant monitor does not mean that the same performance will be achieved on the wafer with different optical properties. The sheet resistance uniformity is not the only the function of the processing temperature but also the function of the processing parameters such as annealing time, rate of heating and cooling, intensity of radiation and its spectral variation as well as function of the optical properties of the processed material. Impact of the substrate on the achieved results and processing dependence are discussed.
