Junction Depth and Sheet Resistance

Ion implantation is often used to form shallow pn junctions for various device applications. The implanted profile approximates a Gaussian distribution, and the junction depth may be found by equating the implanted distribution to the background concentration.

N_pexp[-(x_j - R_p)2/2D R_p²] = N_B

X_j = R_p ± R_{pD Ö} (2ln(N_p/N_B)

Channeling

The LSS results are based on the assumption that the target material is amorphous, having a completely random order. The regular arrangement of atoms in crystal lattice leaves a large amount of open space in the crystal. The figure shows a view through the Si lattice in the <110> direction. The appearance of a random target can be achieved by tilting <100> Si approximately 7 degrees relative to the incoming beam.