Hybrid nanomechanical systems including atom-scale defects based on silicon carbide (NEMSiC)

拟议的项目探索基于碳化硅（SiC）的混合纳米机械系统。特别是，我们将专注于原子级缺陷的纳米机械自由度的耦合。这些缺陷与金刚石中众所周知的NV中心相似。然而，由于SiC的大量多型体，可能的缺陷的种类要多得多。我们的建议专门针对自旋3/2缺陷。与众所周知的金刚石中的自旋1缺陷不同，自旋3/2缺陷可以在不额外施加微波场的情况下被光学检测到。在这个项目的过程中，我们研究了从两种不同的SiC多型体加工的纳米机械谐振器：一方面，我们将研究在不同掺杂的SiC衬底上生长的六边形4 H-SiC。4 H-SiC具有极高的晶体质量，这导致缺陷中心的大自旋相干性。然而，涉及谐振器的制造，并且预期在1，000 - 10，000范围内的中等机械品质因数。另一方面，我们将采用立方3C-SiC。这种材料在强拉伸应力下生长在（111）硅晶片上。这损害了自旋的相干性，但使大的机械品质因数的几十万作为一个结果的大的拉伸stress.We将表征纳米机械谐振器的振动特性从两个，互补的多型体制造。特别强调的是占主导地位的耗散机制（以及占主导地位的张应力，3C-SiC的情况下）。此外，还将利用聚焦离子束辐照的方法，以可控的方式产生缺陷中心，并探讨它们的自旋相干性。该项目的目标是实现一个混合纳米机械系统，其中自旋状态可以被机械地操纵或读出。这将通过光学检测自旋机械共振实验建立。总而言之，我们建议建立碳化硅作为混合自旋纳米机械系统的替代材料，其比流行的单晶金刚石更容易加工。此外，我们将阐明这种新材料选择所带来的潜在优势。4 H-SiC和3C-SiC之间的比较将进一步显示长自旋相干性和高机械品质因数之间的权衡如何可以有利地用于混合纳米机械系统。

The proposed project explores hybrid nanomechanical systems based on silicon carbide (SiC). In particular, we will focus on the coupling of atomic-scale defects to the nanomechanical degree of freedom. These defects bear resemblance to the well-known NV-centers in diamond. However, the variety of possible defects is much higher as a result of the large number of polytypes of SiC. Our proposal specifically targets spin 3/2 defect. Unlike the well-known spin 1 defects in diamond, the spin 3/2 defects can be optically detected without additional application of microwave fields. In the course of the project, we investigate nanomechanical resonators processed from two different SiC polytypes: On the one hand side, we will investigate hexagonal 4H-SiC grown on differently doped SiC substrates. 4H-SiC excels in its extremely high crystal quality, which results in a large spin coherence of the defect centers. However, the fabrication of resonators is involved, and moderate mechanical quality factors in the range of 1,000-10,000 are to be expected. On the other hand side, we will employ cubic 3C-SiC. This material is grown on (111) silicon wafers under strong tensile stress. This impairs the spin coherence, but enables large mechanical quality factors of several 100,000 as a result of the large tensile stress.We will characterize the vibrational properties of nanomechanical resonators fabricated from both, complementary polytypes. Particular emphasis will be on the dominating dissipation mechanisms (as well as the prevailing tensile stress, for the case of 3C-SiC). Even more, the defect centers will be generated by focused ion beam irradiation in controllable manner and their spin coherence will be explored. The goal of the project is the realization of a hybrid nanomechanical system, in which the spin state can be manipulated or read out mechanically. This will be established experimentally via optically detected spin-mechanical resonance. AIl in all, we propose to establish silicon carbide as an alternative material for hybrid spin-nanomechanical systems, which is easier to process than the prevalent single-crystal diamond. In addition, we will shed light on the potential advantages which arise from this new choice of material. The comparison between 4H-SiC and 3C-SiC will further show how the tradeoff between long spin coherence and high mechanical quality factor can be advantageously leveraged for hybrid nanomechanical systems.