skip to main content


Title: Development of hard masks for reactive ion beam angled etching of diamond
Diamond offers good optical properties and hosts bright color centers with long spin coherence times. Recent advances in angled-etching of diamond, specifically with reactive ion beam angled etching (RIBAE), have led to successful demonstration of quantum photonic devices operating at visible wavelengths. However, larger devices operating at telecommunication wavelengths have been difficult to fabricate due to the increased mask erosion, arising from the increased size of devices requiring longer etch times. We evaluated different mask materials for RIBAE of diamond photonic crystal nanobeams and waveguides, and how their thickness, selectivity, aspect ratio and sidewall smoothness affected the resultant etch profiles and optical performance. We found that a thick hydrogen silesquioxane (HSQ) layer on a thin alumina adhesion layer provided the best etch profile and optical performance. The techniques explored in this work can also be adapted to other bulk materials that are not available heteroepitaxially or as thin films-on-insulator.  more » « less
Award ID(s):
1810233 1641064
NSF-PAR ID:
10346399
Author(s) / Creator(s):
; ; ;
Date Published:
Journal Name:
Optics Express
Volume:
30
Issue:
9
ISSN:
1094-4087
Page Range / eLocation ID:
14189
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. In this study, we demonstrate a tolerant and durable Cr/Ni bilayer metal etch mask that allows us to realize approximately 150:1 etch selectivity to diamond. This result is achieved through the use of a very thin initial Cr layer of <10 nm thickness as part of the bilayer metal mask, which results in five to ten times improved selectivity than thick single metal layer masks or bilayer masks with thicker combinations. A finite element analysis was employed to design and understand the physics and working mechanism of the bilayer metal masks with different thicknesses. Raman spectroscopy and energy-dispersive x-ray spectroscopy on the diamond surface were also performed to investigate the changes in diamond quality before and after the deep diamond etching and found that no noticeable etch damage or defects were formed. Overall, this mask strategy offers a viable way to realize deep diamond etching using a high heat and chemistry tolerant and durable bilayer metal etching mask. It also offers several technological benefits and advantages, including various deposition method options, such as sputtering and physical vapor deposition, that can be used and the total thinness of the bilayer metal mask required given the higher selectivity allows us to realize fine diamond etching or high-aspect ratio etching, which is a critical fabrication process for future power, RF, MEMS, and quantum device applications.

     
    more » « less
  2. Wide bandgap II-VI semiconductors, lattice-matched to InP substrates, show promise for use in novel, visible wavelength photonic devices; however, release layers for substrate removal are still under development. An under-etch method is reported which uses an InP substrate as an effective release layer for the epitaxial lift-off of lattice-matched ZnCdMgSe membranes. An array of 100-µm-square membranes is defined on a ZnCdMgSe surface using dry etching and suspended from the InP substrate using a three-step wet etch. The ZnCdMgSe membranes are transfer-printed onto a diamond heatspreader and have an RMS surface roughness < 2 nm over 400 µm2, similar to the epitaxial surface. Membranes on diamond show a photoluminescence peak at ∼520 nm and a thermal redshift of 4 nm with ∼3.6 MWm−2continuous optical pumping at 447 nm. Effective strain management during the process is demonstrated by the absence of cracks or visible membrane bowing and the high brightness photoluminescence indicates a minimal non-radiative defect introduction. The methodology presented will enable the heterogeneous integration and miniaturization of II-VI membrane devices.

     
    more » « less
  3.  
    more » « less
  4. Although Sc doped AlN (ScAlN) has been used extensively in micro-electro-mechanical systems (MEMS) devices and more recently in optical devices, there have not been thorough studies of its intrinsic optical losses. Here we explore the optical losses of the Sc0.30Al0.70N waveguide system by observing racetrack resonator waveguide quality factors. Using a partial physical etch, we fabricate waveguides and extract propagation losses as low as 1.6 ± 0.3 dB/cm at wavelengths around 1550 nm, mostly dominated by intrinsic material absorption from the Sc0.30Al0.70N thin film layer. The highest quality factor of the resonators was greater than 87,000. The propagation loss value is lower than any value previously published and shows that this material can be broadly used in optical modulators without significant loss.

     
    more » « less
  5. The fixed post-manufacturing properties of metal-based photonic devices impose limitations on their adoption in dynamic photonics. Modulation approaches currently available (e.g. mechanical stressing or electrical biasing) tend to render the process cumbersome or energy-inefficient. Here we demonstrate the promise of utilizing magnesium (Mg) in achieving optical tuning in a simple and controllable manner: etching in water. We revealed an evident etch rate modulation with the control of temperature and structural dimensionality. Further, our numerical calculations demonstrate the substantial tuning range of optical resonances spanning the entire visible frequency range with the etching-induced size reduction of several archetypal plasmonic nanostructures. Our work will help to guide the rational design and fabrication of bio-degradable photonic devices with easily tunable optical responses and minimal power footprint.

     
    more » « less