Grain boundaries in semiconductors

Single-electron effects in heavily doped polycrystalline silicon nanowires

“…The differences in electrical behavior between polycrystalline and crystalline silicon wires of nominally identical geometry suggest a strong influence from polysilicon grain boundaries, which will contain a high concentration of electrically active defect states, segregated dopants, and other impurities. 10,11 Large numbers of carriertrapping states pin the Fermi level even for high doping levels, 12 creating a potential barrier at the grain boundary. Pinning of the Fermi level strongly attenuates gate action in polysilicon films 13 and the defect states provide an electrostatic screening mechanism.…”

“…Since we observe a sharp reduction in the screening as the gate bias sweeps from negative to positive bias, this implies a corresponding step in the interface density of states at the Fermi level near zero bias. The density of states relation at a grain boundary is not straightforwardly predictable, 10 but experimental evidence exists for discrete electronic levels at silicon grain boundaries. 14 In our system, in addition to a continuum of grain boundary traps in the band gap, there may be a narrow band of states associated with a high density of impurity species, possibly phosphorus or oxygen.…”

Cooperative Chemical Rebonding In The Segregation Of Impurities In Silicon Grain Boundaries

“…From ab initio calculations we estimated A1 -0.1 eV for all triangles, and A2 -0.3 eV and c 0.1 eV respectively for the bright (2) and dark (1,3) triangles. Assuming an equilibrium temperature of 700°C and a bulk As concentration of -0.4% (close to the heavy doping limit of As in crystalline Si), the total As concentration (nG -nl + n2)…”

Cs diffusion in SiC high-energy grain boundaries

“…Modeling of the HEBGs, often called disordered GBs, has been a great challenge in covalent materials 25 . In this work we follow the approach of Ref.…”