Here we report on successful synthesis of Ge-doped single crystal diamond at high-pressure high-temperature (HPHT) conditions of 7.0 GPa and 1500-1900 degrees C from an Mg-Ge-C system. The systematic study of diamond crystallization processes reveals that addition of Ge to the Mg-C system suppresses the intensity of diamond spontaneous nucleation enabling synthesis of relatively large (2-3 mm) diamond crystals via seeded growth. Temperature is found to be a key factor controlling diamond crystallization mechanisms, morphological characteristics, and optical properties of the crystals. It is established that the diamond growth rate depends almost exponentially on the temperature increasing from 3.3 mu m/h at 1500 degrees C to 4.2 mm/h at 1900 degrees C. Spectroscopic characterization of the synthesized diamonds reveals the abundance of the 2.06 eV Ge-V centers in the photoluminescence spectra confirming successful doping of the diamonds with germanium. The feasibility of the Mg-Ge-C system for growing bulk low-strain diamond doped with isotopically enriched germanium is demonstrated. The isotopic shift of the zero-phonon lines of the 2.06 eV center and the newly observed 1.747 eV center is found, proving the involvement of germanium atoms in the structure of the corresponding defects.
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机译：在这里，我们报道了Mg-Ge-C系统在7.0 GPa和1500-1900摄氏度的高压高温（HPHT）条件下成功合成了掺锗的单晶金刚石的过程。金刚石结晶过程的系统研究表明，向Mg-C系统中添加Ge可以抑制金刚石自发成核的强度，从而可以通过晶种生长合成相对较大（2-3毫米）的金刚石晶体。发现温度是控制金刚石结晶机制，形态特征和晶体光学性质的关键因素。可以确定的是，金刚石的生长速度几乎成倍地取决于温度，即温度从1500摄氏度的3.3微米/小时增加到1900摄氏度的4.2毫米/小时。合成金刚石的光谱表征表明，其丰度为2.06 eV Ge-在光致发光光谱中的V中心证实了锗中金刚石的成功掺杂。证明了Mg-Ge-C系统用于生长掺有同位素富集锗的块状低应变金刚石的可行性。发现了2.06 eV中心的零声子线和新近观测到的1.747 eV中心的同位素位移，证明了锗原子参与了相应缺陷的结构。
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