The surface potential control is important because the surface potential is positive,
electron to be depleted on the near-surface region.
D- is in T site and T site is expanded to the size of D-.
D+ is close to T site and D+ will be hopped to T site and D- and D+ are combined to be D2 gas.
and D2 are pushed and squeezed to 1A(original size of T site) so
D2 turned to femto-D2 due to the hydrogen deep orbit
Here is the femto hydrogen and femto hydrogen atom.
The size of femto hydrogen is on the order of femto meter.
So femto hydrogen can have the perfect shielding of the coulomb repulsive force between protons(below)
D+ is hopped to D- in T site and D2 are created.
D2 to be squeezed to 1A and this cause the femto D2 creation.
Thus D+ implantation can trigger cold fusion due to the sufficiently high incident energy.