Quantitative analytical spectroscopy of ultra-high purity germanium crystals

高纯度和设计的低掺杂和共掺杂半导体晶体是材料研究的热点。这包括生产这种晶体以及表征它们的技术。这种高质量的晶体对基础和应用研究和发展都很重要。未掺杂的锗（Ge）被广泛用作光学窗口、滤光片以及电离辐射的探测器，特别是x射线和伽马射线。低掺杂锗晶体是单电子导电介质的极好天然模拟物，其中许多处理单电子方法的物理模型可以通过实验验证。迄今为止，大多数基于锗的低维材料（量子点和结构）被认为是用于单电子系统和量子技术。低掺杂或残余掺杂的Ge为实验获得理论单电子模型提供了独特的可能性，这是电活性杂质能谱理论建模的主要方法。该项目是莱布尼茨研究所<s:1> kristallz<e:1> chtung （IKZ）和Humboldt-Universität zu Berlin （HUB）研究小组的共同努力。两个团队的加入是为了充分利用他们互补的专业知识。IKZ提案的重点是制作高质量的锗晶体，考虑到锗主体晶格、掺杂剂和同位素组成。HUB团队专注于锗晶体的光谱表征（例如光学常数，掺杂剂浓度）。该合作项目HUB部分的目标是建立用于表征超纯、低掺杂和未掺杂单晶锗的高灵敏度分析光谱。该项目将提供具有可变同位素含量的高纯度晶体。通过测量这些晶体在超低浓度电活性杂质下的能谱，可以对其进行精确分析。此外，它将提供杂质与宿主晶格，局部模式，晶体缺陷和同位素含量影响的相互作用的见解。

High-purity and by design low-doped and co-doped semiconducting crystals are of great interest for material research. This includes techniques to produce such crystals as well as to characterize them. Such high quality crystals are important for both, fundamental and applied research and development. Undoped germanium (Ge) is widely used as optical windows, filters as well as detectors of ionizing radiation, particularly x-rays and gamma rays. Low-doped Ge crystals are excellent natural analogue of a single-electron conducting medium, where many physical models dealing with a single-electron approach can be experimentally verified. To date, mostly Ge-based low-dimensional materials (quantum dots and structures) are considered for single-electron systems and quantum technologies. Low-doped Ge or Ge with residual doping offers a unique possibility to experimentally access the theoretical single-electron model, which is a main approach for theoretical modelling energy spectra of electrically active impurities. The project is a joint effort of the research groups at the Leibniz-Institut für Kristallzüchtung (IKZ) and Humboldt-Universität zu Berlin (HUB). Both teams join in order to make the best use of their complementary expertise. The focus of the IKZ proposal is on making high-quality Ge crystals, with respect to the Ge host lattice, dopants and isotopic composition. The HUB team focusses on the spectroscopic characterization of the Ge crystals (e.g. optical constants, concentration of dopants). The goal of the HUB part of this cooperation project is to establish high-sensitivity analytical spectroscopy for characterization of ultra-pure, low-doped and undoped monocrystalline Ge. The project will deliver high-purity crystals with variable isotopic content. These crystals are precisely analyzed by measuring their energy spectra at ultra-low concentrations of electrically active impurities. Besides that, it will provide insights into impurity interactions with the host lattice, local modes, crystal defects and influence from isotope content.