Crystallization of Ge and Si in metal films. I

Abstract

The behavior of amorphous Si in contact with Ag films and Ge in contact with Al films has been studied at temperatures well below those at which any liquid phase is present. MeV 4He+ ion backscattering techniques, transmission electron diffraction, scanning electron microscopy, and electron microprobe analysis have been used. We find that of the many possible reactions which carry the amorphous Si or Ge into their crystalline forms the reaction predominating under our experimental conditions consists of dissolution, diffusion, and crystal growth. During isothermal heat treatment, the semiconductor film is dissolved into the metal film where it diffuses and precipitates as crystalline Si or Ge. These processes are solid-solid reactions, since this behavior is observed over temperatures of 300°C to as low as 100°C for GelAI, compared to the 424°C eutectic in this system. In Sil Ag, this behavior was observed from 700 to 400°C, compared with the 840°C eutectic.

Microstructural evolution of oxides and semiconductor thin films

“…Furthermore, the studies of such materials microstructure have important technological implications concerning the formation and control of materials systems of desired properties, such as thin films, nanojets [265], nanowires [266], and other surface supported structures. A strong interest in reactions occurring in thin film systems exists, not only in view of the practical interest, for example, the microelectronics industry, but also because of great scientific interest [250][251][252]. It is well known that fractal formation is accompanied by lateral interdiffusion between metal (Au, Ag, Al, or Pd) atoms and semiconductor (Ge or Si) atoms at short range, which is close to the spacing of branches of the fractal [253][254][255].…”

“…The formation, evolution, and consequences of nonequilibrium growth processes in materials systems have been the subject of fruitful inquiry for a long time [250][251][252][253][254][255][256][257][258][259][260][261][262][263][264]. These investigations have been performed in various disciplines, such as thermodynamics, statistical physics, and materials science, and have been applied to systems characterized by different length scales, from the macroscopic to the nanoscale regimes [265].…”

Influence of the (111) twinning on the formation of diamond cubic/diamond hexagonal heterostructures in Cu-catalyzed Si nanowires

“…Al, In, and Au have been claimed to form eutectics with Si, whereas Pd and Ni are accepted to form various silicides with Si which enhance the incorporated Si atoms in a crystallized structure. 24,25 Many efforts have been centered to find other appropriate metal catalysts compatible with device processing. 26 Among the different candidates, copper has been reported to interact in a different way with silicon atoms than those other metal catalysts forming eutectics ͑gold͒ and silicides ͑nickel͒.…”

Ion Implanted N-Type Contact for High-Purity Germanium Radiation Detectors

“…The dramatic improvement of our contact achieved by use of this cleaning process strongly suggests that unannealed damage beyond the phosphorous doped region, created by knock-on of the light ions (oxygen, fluorine, nitrogen) composing surface contaminants, is the source of excessive reverse currents. Residual radiation damage inside the heavily doped layer is either removed more completely by donor-vacancy 9 complex formation or is overcompensated by the electrically active donor concentration.…”

“…Thin large-area n+ contacts on high-purity germanium detectors have been produced by implantation of 25 keV phosphorous ions. The contacts show leakage current of < 10- 9 A up to fields of > 2000 V/cm. Unannealed lattice damage may still limit the maximum applied field, but proper surface treatment prior to implantation and subsequent annealing steps have resulted in a dramatic improvement in the applied field.…”