M. N. Miheev Institute of Metal Physics, Russian Academy of Sciences, Urals Division, 18 S. Kovalevskaya Str., Yekaterinburg 620137, Russia.
Bayerisches Geoinstitut, Universität Bayreuth, Universitätsstrasse 30, Bayreuth D-95447, Germany.
Sci Rep. 2017 Mar 14;7:44220. doi: 10.1038/srep44220.
Controlled tuning the electrical, optical, magnetic, mechanical and other characteristics of the leading semiconducting materials is one of the primary technological challenges. Here, we demonstrate that the electronic transport properties of conventional single-crystalline wafers of germanium may be dramatically tuned by application of moderate pressures. We investigated the thermoelectric power (Seebeck coefficient) of p- and n-type germanium under high pressure to 20 GPa. We established that an applied pressure of several GPa drastically shifts the electrical conduction to p-type. The p-type conduction is conserved across the semiconductor-metal phase transition at near 10 GPa. Upon pressure releasing, germanium transformed to a metastable st12 phase (Ge-III) with n-type semiconducting conductivity. We proposed that the unusual electronic properties of germanium in the original cubic-diamond-structured phase could result from a splitting of the "heavy" and "light" holes bands, and a related charge transfer between them. We suggested new innovative applications of germanium, e.g., in technologies of printing of n-p and n-p-n junctions by applied stress. Thus, our work has uncovered a new face of germanium as a 'smart' material.
控制调整主导半导体材料的电学、光学、磁学、力学和其他特性是主要技术挑战之一。在这里，我们证明了通过施加适度压力，可以显著调整传统单晶锗片的电子输运特性。我们研究了 p 型和 n 型锗在高达 20 GPa 的高压下的热电功率（塞贝克系数）。我们确定，几 GPa 的外加压力会剧烈地将电导转变为 p 型。在接近 10 GPa 的半导体-金属相变过程中，p 型传导得以保持。在压力释放后，锗转变为具有 n 型半导体导电性的亚稳 st12 相（Ge-III）。我们提出，原始立方金刚石结构相的锗的异常电子性质可能源于“重”和“轻”空穴带的分裂，以及它们之间的相关电荷转移。我们提出了锗的新的创新应用，例如，通过施加应力在印刷 n-p 和 n-p-n 结的技术中应用。因此，我们的工作揭示了锗作为一种“智能”材料的新面貌。
