Correlated PL, Raman and IR nanospectroscopy for studying single-photon emitters in hBN

该项目旨在利用近场技术研究六方氮化硼(HBN)中的单光子发射体(SPE)。单光子发射体对未来的量子技术至关重要，因为未来的量子技术需要按需单光子。对于未来的应用，SPE必须满足特殊要求，例如，它们应该在室温下稳定，能量可调。六方氮化硼(HBN)中的色心是实现这一点的固相外延，其性质目前还不完全清楚。例如，人们预计应变会对它们的发射特性产生重大影响，但其潜在的机制仍不清楚。通过研究空间分辨率远高于光学衍射极限的SPE的基本性质，可以获得新的见解。为此，我想利用红外纳米成像和纳米光谱技术(分别为S纳米光学显微镜和纳米傅里叶变换红外光谱)以及针尖增强拉曼光谱和针尖增强光致发光光谱，在纳米尺度的空间分辨率上研究hBN中SPE的局域应变和光致发光之间的相互作用。为了对这些技术提供的互补信息进行最可靠的关联，该项目旨在开发一种纳米FTIR和TERS相结合的装置，首次允许同时测量纳米级分辨率的红外光谱、拉曼光谱和荧光光谱。还计划在通过在发射体附近产生宏观应变场来操纵发射体的光学特性之后进行这些研究，例如通过纳米刻蚀。这一发现将有助于更好地理解应变对发射体的起源、激活和跃迁能的影响。拟议的研究将在西班牙圣塞巴斯蒂安CIC NanGUNE的纳米光学小组进行，该小组由Rainer Hillenbrand领导，他开创了S-SNOM和纳米FTIR的开发和应用(例如映射hBN中的声子极化子)。该小组还证明了纳米FTIR仪器非常适合于TERS和TEPL测量，这两种测量是并行开发的，但分别用于S-SNOM和纳米FTIR。我的研究目前位于半导体光学机械领域，重点是应变2D材料的发光和吸收研究。此外，我还通过拉曼光谱研究了这些材料的声子性质，并将它们与它们的光致发光关联起来。最近，我研究了应变对单层和双层膜的影响，发现它可以通过激子-声子耦合来控制光学性质。我还与WSe2单层中的SPE一起工作，这是我通过生成纳米级应变分布而确定地创建的。我相信，我在光学机械和SPE方面的背景，加上CIC NanGUNE的设备和专业知识，将导致拟议项目的成功实施。

This proposed project aims on studying single photon emitters (SPEs) in hexagonal boron nitride (hBN) with the help of near-field techniques providing nanoscale spatial resolution.SPEs are essential for future quantum technologies, where single photons on demand are needed. For future applications, SPEs must fulfill special requirements, e.g., they should be stable at room temperature and tunable in energy. SPEs that fulfill these aspects are color centers in hexagonal boron nitride (hBN), whose characteristics are not fully understood yet. For example, it is expected that strain has a major influence on their emission properties, but the underlying mechanisms are still not understood. Novel insights might be achieved by studying the fundamental SPE properties with a spatial resolution much better than the optical diffraction limit. For that reason, I want to use infrared nanoimaging and nanospectroscopy techniques (s-SNOM and nano-FTIR, respectively) as well as tip-enhanced Raman spectroscopy (TERS) and tip-enhanced photoluminescence spectroscopy (TEPL) to study the interplay between local strain and photoluminescence (PL) of SPEs in hBN with nanoscale spatial resolution. For a most reliable correlation of the complementary information provided by these techniques, the project aims on developing a combined nano-FTIR and TERS setup, allowing, for the first time, for simultaneous measurements of nanoscale-resolved infrared, Raman and PL spectra. It is also planned to perform theses studies after manipulation of the emitters’ optical properties by creating macroscopic strain fields in their vicinity, for example via nanointendation. The findings will help for a better understanding of the influence of strain on the emitters´ origin, activation and transition energy.The proposed research will be carried out in the nanooptics group at CIC nanoGUNE (San Sebastian, Spain), which is led by Rainer Hillenbrand, who pioneered the development and application (e.g. mapping phonon polaritons in hBN) of s-SNOM and nano-FTIR. The group also demonstrated that the nano-FTIR instrumentation is well suited for TERS and TEPL measurements, which so far have been developed in parallel, but separately, to s-SNOM and nano-FTIR.My research is currently located in the field of optomechanics of semiconductors, focusing on the PL and absorption studies of strained 2D materials. Besides, I am studying the phononic properties of these materials via Raman spectroscopy and correlate them with their PL. Recently, I investigated the influence of strain on mono- and bilayers and showed that it can be used to manipulate the optical properties via exciton-phonon coupling. I also worked with SPEs in WSe2 monolayers, which I created deterministically by generating nanoscale strain profiles.I am convinced that my background in optomechanics and SPEs combined with the equipment and expertise at CIC nanoGUNE will lead to a successful implementation of the proposed project.