IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Tuesday Sessions
       Session SC-TuM

Paper SC-TuM9
Growth and Electrical Characterization of Ultra-Dense Phosphorous Delta-Doping Layers in Silicon

Tuesday, October 30, 2001, 11:00 am, Room 124

Session: Semiconductor Interfaces and Thin Films
Presenter: T.-C. Shen, Utah State University
Authors: T.-C. Shen, Utah State University
J.-Y. Ji, Utah State University
M. Zudov, University of Utah
R.-R. Du, University of Utah
J.S. Kline, University of Illinois
J.R. Tucker, University of Illinois
Correspondent: Click to Email
If dopant atoms substitute a substantial fraction of a monolayer of the Si atoms within a crystal, the resulting 2D dopant sheet may provide unique electrical properties for novel nano-scale devices. We have demonstrated that depositing phosphine molecules onto Si(100) surfaces in ultrahigh vacuum, followed by 35-50ML of Si epitaxy at T<500K, can yield a conducting layer that does not freeze out even at 0.3K. At 1/4ML saturation coverage at room temperature, the positive phosphorous ions create very large electric fields in the growth direction, producing a tightly confined 2D electron system. Within the plane, however, wavefunctions for these bound electrons are expected to couple across relatively large distances of a few Bohr radii (~2.5nm for P-atom donors), opening up new possibilities for lateral tunnel junctions. Initial magnetotransport measurements reveal an electron density of ~ 2.6x10@super 14@cm@super -2@ (~1/4ML) at 0.3K indicating complete electrical activation of the donor layer. From 60 to 0.3K the sheet resistance grows logarithmically with decreasing T, yielding a resistance of 1.16 k@ohm@/sq and a mobility of 21cm@super 2@/Vs at 0.3K. Studies of the correlation between electrical characteristics and phosphine deposition parameters will be presented. In addition, a new paradigm for devices based on selectively patterned 2D electron/hole systems will be discussed.