Growth and Fundamental Properties of GeSi Bulk Crystals

锗硅（Ge_<1-x>Si_x或Germanium-silicon Si_xGe_<1-x>）合金是金刚石基的完全可混溶的固溶体，并且由于其提供的带隙和晶格参数工程的潜力而作为微电子和光电子器件的材料引起了人们的极大兴趣。这项研究已经进行，以建立高品质的GeSi合金单晶的生长和澄清的各种基本属性所带来的合金化和探索的内在特性和潜力，这种材料的广泛应用的可能性。（1）采用提拉法，在0&lt;x&lt;0.15和0.73&lt;x&lt;1的合金中获得了直径大于25 mm、长度大于40 mm的大尺寸完整单晶。还成功地获得了重掺杂有浓度高达10 μ cm-3的电活性杂质的SiGe合金（0.80&lt;x&lt;1）单晶<20><-3>。(2)By XAFS研究 ...更多信息 在局部原子结构上，已知GeSi合金具有Si和Ge原子的随机替代占位，但在整个组成范围内没有优先有序，并且Ge-Ge和Ge-Si键长保持明显不同的长度，并随合金组成线性变化，不完全Pauling情况。（3）氧杂质在最大浓度为10 μ <18>cm ~ 2<-3>时优先占据Si原子间的键心位置，形成Si-O-Si准分子。（4）合金的机械强度在升高的温度下变得对温度不敏感，并且取决于成分，在整个成分范围内与x（1-x）成比例，这可能源于与合金成分的微观波动和位错之间的动态相互作用有关的内建应力场。（5）研究了重掺杂GeSi的电导率、热导率和Seebeck系数，为开发高温热电转换器提供了理论依据。少

Germanium-silicon (Ge_<1-x>Si_x or Germanium-silicon Si_xGe_<1-x>) alloy is a fully miscible solid solution of the diamond-base and has attracted keen interest as material for both microelectronic and opto-electronic devices in view of the potential for band gap and lattice parameter engineering they offer. This research has been undertaken in order to establish the growth of high quality single crystals of GeSi alloys and to clarify the various fundamental properties that are brought about by alloying and the possibility of exploring the intrinsic properties and potentials of this material for wide applications.(1)Full single crystals of large size, larger than 25 mm in diameter and longer than 40 mm in length, were obtained for the alloys of composition 0<x<0.15 and 0.73<x<1 by the Czochralski technique. Single crystals of SiGe alloys (0.80<x<1) heavily doped with electrically active impurities with a concentration up to 10^<20>cm^<-3> were also successfully obtained.(2)By XAFS study … More on the local atomic structure, it is known that GeSi alloy possess random substitutional site occupancy of Si and Ge atoms but no preferential ordering across the whole composition range and that Ge-Ge and Ge-Si bond lengths maintain distinctly different lengths and vary linearly with alloy composition, to he incomplete Pauling case.(3)Oxygen impurities in the concentration of 10^<18>cm^<-3> maximum occupy preferentially a bond-center site between Si atoms to make a Si-O-Si quasi-molecule.(4)The mechanical strength of the alloys becomes temperature-insensitive at elevated temperatures and depends on the composition, being proportional to x(1-x) over the whole composition range, which may be originating in the built-in stress fields related to microscopic fluctuation of alloy composition and the dynamic interaction between dislocations.(5)Electrical and thermal conductivities and Seebeck coefficient in heavily impurity doped GeSi were evaluated for develop thermoelectric converters available at elevated temperatures. Less