MeV Si Implantation Research Articles

Density Measurements of Ion Implanted Amorphous Silicon

ABSTRACTThe density of amorphous Si was measured. Continuous and buried amorphous Si films were produced by 0.5-8 MeV Si implantation through a steel contact mask. Surface steps of amorphous Si stripes with initial thicknesses from 0.9 to ∼ 5.0 μm were measured using a surface profilometer. For implants up to 5 MeV, the amorphous Si is constrained laterally by the surrounding crystal and deforms plastically. The density of amorphous Si deduced from the surface step heights is 4.91 × 1022 cm-3, 1.7 ± 0.1 % less than the density of crystal Si (5.00 × 1022 cm-3).

Defect Structure of MEV Si Implantation in GaAs

ABSTRACTThe defect and atomic profiles for MeV implantation of Si in GaAs were investigated using He++ channeling, TEM, and SIMS. Doses of 1–10 × 1015Si/cm2 at 1–3 MeV were used. MeV implantation at room temperature rendered only a small amount of lattice disorder in GaAs. Upon annealing at 400°C for 1 h or 800°C for 30 a, we observed a ‘defect-free’ surface region (- 1 μ for 3 MeV implant). Below this region, extensive secondary defects were formed in a band which was 0.7 μ wide and centered at 2 μ for 3 MeV implant. These defects were mostly dislocations lying in the [111] plane. SIMS depth profiles of Si implants showed the Si peak to be very close to the peak position of the defects. The experimental profiles of Si were compared to the TRIM calculation; generally good agreement existed among the peak positions.

MeV Si implantation in GaAs

The formation of n-type layers in semi-insulating, LEC GaAs by MeV Si implantation has been investigated using an electrolytic CV technique. The study has been done as a function of dose and anneal temperature. The carrier concentration profile associated with 2.5 × 10 13/cm 2, MeV Si implant was not greatly affected by varying the anneal temperature from 750°C to 840°C. The percentage of activation was 65% for 2.5 × 10 13 Si/cm 2 and 40% for 5 × 10 13 Si/cm 3. A buried n-layer with a peak carrier concentration at 2.9 μm was formed with 6 MeV Si implantation. The peak carrier concentration obtained with 4.2 × 10 13 Si/cm 2 implants was 30% higher with an 850°C anneal than with a 750°C. The percentage of activation was sensitive to dose, decreasing for a dose greater than 4.2 × 10 13 Si/cm 2. A 3 μm, 2 × 10 16/cm 3 n-type layer has been produced using multiple MeV Si implantation.