Strain Engineering of Diamond Microstructures by Trench Filling and Oxidation

Diamond is considered as the “Mount Everest” of electronic, photonic, and quantum materials due to its outstanding properties, such as an ultrawide bandgap, ultrahigh thermal conductivity, ultrahigh dielectric breakdown strength, high carrier mobility, and hosts of quantum emitters. However, difficulty in doping due to deep dopant levels, indirect bandgap, and difficulty in controlling the color centers’ quantum levels have posed significant challenges to fully utilize diamond in electronic, photonic, and quantum applications. Based on recent theoretical predictions, the bandgap of diamond can be significantly tuned given enough strain. Additionally, it has been demonstrated that strain can manipulate the energy levels in color centers. Therefore, the ability to engineer strain in diamond can be a game changer for diamond based electronics, photonics and quantum applications. However, being the hardest material, diamond is notoriously difficult to strain. Here we present a novel, in-situ, and integrated approach to strain engineer diamond microstructure by growth and oxidation of material (e.g. Si, Al) filled in the micro-fabricated diamond trench. In this study, pairs of diamond fins are fabricated and the trench between fins is filled by poly-Si or Al. The oxidation of trench-filling material exerts stress on the diamond microstructures as a consequence of increased material volume and produces mechanical strain on the microstructures. We will present strain analysis on diamond microstructures as a function of trench dimension, oxidation temperature, and oxidizing materials as measured by electron microscopy and Raman spectroscopy.<br/><i>Sandia National Laboratories is </i><i>managed and operated by NTESS under DOE NNSA contract DE-NA0003525.</i><br/><i>(SAND #: SAND2022-8136 A)</i>