A variety of nanoscale photonic, mechanical, electronic, and optoelectronic devices require scalable thin film fabrication. Typically, the device layer is defined by thin film deposition on a ...substrate of a different material, and optical or electrical isolation is provided by the material properties of the substrate or by removal of the substrate. For a number of materials this planar approach is not feasible, and new fabrication techniques are required to realize complex nanoscale devices. Here, we report a three-dimensional fabrication technique based on anisotropic plasma etching at an oblique angle to the sample surface. As a proof of concept, this angled-etching methodology is used to fabricate free-standing nanoscale components in bulk single-crystal diamond, including nanobeam mechanical resonators, optical waveguides, and photonic crystal and microdisk cavities. Potential applications of the fabricated prototypes range from classical and quantum photonic devices to nanomechanical-based sensors and actuators.
The realization of efficient optical interfaces for solid-state atom-like systems is an important problem in quantum science with potential applications in quantum communications and quantum ...information processing. We describe and demonstrate a technique for coupling single nitrogen vacancy (NV) centers to suspended diamond photonic crystal cavities with quality factors up to 6000. Specifically, we present an enhancement of the NV center’s zero-phonon line fluorescence by a factor of ∼7 in low-temperature measurements.
We demonstrate an integrated nanophotonic network in diamond, consisting of a ring resonator coupled to an optical waveguide with grating in- and outcouplers. Using a nitrogen-vacancy color center ...embedded inside the ring resonator as a source of photons, single photon generation and routing at room temperature is observed. Furthermore, we observe a large overall photon extraction efficiency (10%) and high quality factors of ring resonators (3200 for waveguide-coupled system and 12 600 for a bare ring).
Oxide and nitride thin-films of Ti, Hf, and Si serve numerous applications owing to the diverse range of their material properties. It is therefore imperative to have proper control over these ...properties during materials processing. Ion-surface interactions during plasma processing techniques can influence the properties of a growing film. In this work, we investigated the effects of controlling ion characteristics (energy, dose) on the properties of the aforementioned materials during plasma-enhanced atomic layer deposition (PEALD) on planar and 3D substrate topographies. We used a 200 mm remote PEALD system equipped with substrate biasing to control the energy and dose of ions by varying the magnitude and duration of the applied bias, respectively, during plasma exposure. Implementing substrate biasing in these forms enhanced PEALD process capability by providing two additional parameters for tuning a wide range of material properties. Below the regimes of ion-induced degradation, enhancing ion energies with substrate biasing during PEALD increased the refractive index and mass density of TiO x and HfO x and enabled control over their crystalline properties. PEALD of these oxides with substrate biasing at 150 °C led to the formation of crystalline material at the low temperature, which would otherwise yield amorphous films for deposition without biasing. Enhanced ion energies drastically reduced the resistivity of conductive TiN x and HfN x films. Furthermore, biasing during PEALD enabled the residual stress of these materials to be altered from tensile to compressive. The properties of SiO x were slightly improved whereas those of SiN x were degraded as a function of substrate biasing. PEALD on 3D trench nanostructures with biasing induced differing film properties at different regions of the 3D substrate. On the basis of the results presented herein, prospects afforded by the implementation of this technique during PEALD, such as enabling new routes for topographically selective deposition on 3D substrates, are discussed.
A plasma-enhanced atomic layer deposition (ALD) process was developed for the growth of SiNx thin films using Si2Cl6 and NH3 plasma. At substrate temperatures ≤400 °C, we show that this ALD process ...leads to films with >95% conformality over high aspect ratio nanostructures with a growth per cycle of ∼1.2 Å. The film growth mechanism was studied using in situ attenuated total reflection Fourier transform infrared spectroscopy. Our data show that on the SiNx growth surface, Si2Cl6 reacts with surface -NH2 groups to form surface -NH species, which are incorporated into the growing film. In the subsequent half cycle, radicals generated in the NH3 plasma abstract surface Cl atoms, and restore an NHx (x = 1,2)-terminated surface. Surface Si-N-Si bonds are also primarily formed during the NH3 plasma half-cycle. The infrared data and Rutherford backscattering combined with hydrogen forward scattering shows that the films contain ∼23% H atoms primarily incorporated as -NH groups.
The realization of an integrated diamond photonic platform, based on a thin single crystal diamond film on top of a silicon dioxide/silicon substrate, is reported. Using this approach, we demonstrate ...high-quality factor single crystal diamond race-track resonators, operating at near-infrared wavelengths (1550 nm). The devices are integrated with low-loss diamond waveguides terminated with polymer pads (spot size converters) to facilitate in- (out-) coupling of light from (to) an optical fiber. Optical characterization of these resonators reveal quality factors as high as ∼250 000 and overall insertion losses as low as 1 dB/facet. Scattering induced mode splitting as well as signatures of nonlinear effects such as optical bistability are observed at an input pump power of ∼100 mW in the waveguides.
Background Healthcare experiences associated with perceived racial/ethnic discrimination among patients are poorly understood. Objective Identify domains of patient dissatisfaction associated with ...perceived racial/ethnic discrimination among patients with pain. Design Semi-structured telephone surveys completed in 2013–2015. Participants White, African American, and Latino participants who reported receiving pain management from 25 Veterans Affairs (VA) Medical Centers. Main measures Surveys included open-ended questions about healthcare satisfaction/dissatisfaction and a measure of perceived racial/ethnic-based discrimination while seeking VA healthcare. Binary indicators for ten qualitative domains of dissatisfaction were derived from open-ended questions. We used multilevel models to identify dissatisfaction domains associated with perceived discrimination, adjusting for patient characteristics and site. Within domains associated with discrimination, we identified the most frequent codes and examined whether patients primarily referenced clinical or non-clinical staff in their experiences. Key results Overall, 622 participants (30.4% White, 37.8% African American, 31.8% Latino; 57.4% female; mean age = 53.4) reported a median discrimination score of 1.0 (IQR: 1.0–1.3) on a scale of 1 to 5; 233 (37.5%) perceived any racial/ethnic discrimination in healthcare. Individually, 7 of 10 qualitative domains were significantly associated with perceived discrimination: dissatisfaction with care quality, facilities, continuity of care, interactions with staff, staff demeanor, unresolved pain, and pharmacy services (ps<0.005). In combined models stratified by racial/ethnic group, 3 domains remained statistically significant: poor interactions for Latinos (adjOR = 5.24, 95% CI = 2.28–12.06), negative demeanor for African Americans (adjOR = 2.82, 95% CI = 1.45–5.50), and unresolved pain for Whites (adjOR = 6.23, 95% CI = 2.39–16.28). Clinical staff were referenced more often than non-clinical staff for all domains (interactions: 51% vs. 30%; demeanor: 46% vs. 15%; unresolved pain: 18% vs. 1%, respectively). Conclusion Negative interpersonal experiences and unresolved pain are strong correlates of perceived racial/ethnic discrimination among patients with pain. Future studies should test whether interventions targeting these domains reduce patient perceptions of racial/ethnic discrimination in healthcare.
Highlights • Lateralized reaction times in a go/no-go task vary across the menstrual cycle. • Anterior cingulate cortex is less activated during go/no-go task in the luteal phase. • Functional ...organization of selective attention network is modulated by cycle phases.
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