Molecular Strategies for Configurational Sulfur Doping of Group IV Semiconductors Grown on Si(100) Using S(MH3)2 (M = Si,Ge) Delivery Sources: An Experimental and Theoretical Inq
详细信息 查看全文
- 作者：J. Kouvetakis ; R. Favaro ; G. J. Grzybowski ; C. Senaratne ; J. Men茅ndez ; A. V. G. Chizmeshya
- 刊名：Chemistry of Materials
- 出版年：2014
- 出版时间：August 12, 2014
- 年：2014
- 卷：26
- 期：15
- 页码：4447-4458
- 全文大小：494K
- ISSN：1520-5002
文摘
We report a new doping protocol of pure Ge films grown on Si and related Si/Sn materials based on S delivered from high reactivity hydride molecules S(MH3)2 (M = Si,Ge). The new doping strategy targets next generation semiconductor applications requiring enhanced IR optical performance as well as high-mobility field effect transistors fully integrated with silicon. To explore this paradigm, we first developed a practical and straightforward synthesis approach, which avoids the use of toxic starting materials and yields viable quantities of the title compounds. These were then used to carry out proof-of-concept low-temperature depositions of Ge/Si(100) and GeSn/Si(100) films, doped with 鈥渄ouble donor鈥?S atoms for the first time. These systems are characterized using standard materials science techniques via RBS, XTEM, SIMS, and XRD for structure, composition, and crystallinity, and their electrical properties are measured by the Hall method. Thermally robust dopant levels <1018 are systematically obtained using a range of process protocols, which can be further optimized for practical applications. Complementary first-principles density functional theory simulations were then used to study the stability and strain associated with the incorporation of S within the parent lattice as molecular fragments such as Ge鈥揝鈥揋e, Ge鈥揝, Si鈥揝鈥揝i, and Si鈥揝 derived from the S(SiH3)2 and S(GeH3)2 molecular sources. Completely incorporated Ge鈥揝鈥揋e or Ge鈥揝 units in Ge in which S resides in either substitutional (tetrahedral) or near-substitutional (3-coordinate) sites are predicted to be strongly bound (鈭?.36 eV and 鈭?.49 eV, respectively) relative to interstitial S and isolated Ge vacancies, while the corresponding binding in Si鈥揝鈥揝i and Si鈥揝 analogs is slightly enhanced. By considering the induced lattice strain, binding energy, and the structural accommodation of molecular core bonds, plausible defect-clusters are identified and tentatively used to correlate sulfur concentrations and carrier concentrations trends. In the case of the S(GeH3)2 grown films, a mixture of deep and shallow donor centers must be invoked to account for the observed carrier concentration enhancement.