Effect of electric charge accumulation on low energy ion implantation in insulators
Abstract
Charge accumulation at the surface of insulators during low energy ion implantation is related to two processes: ion impinging on the sample and secondary electron emission. Samples composed of a piece of Si (having the size of the ion beam) fixed on the centre of polyethylene (PE) coupons have been implanted with 2.2 keV H2 ions to a fluence of 2 × 1016 H/cm2. ERD (Elastic Recoil Detection) depth profiles of the implanted ions are shallower with an increase of the PE coupon size. The relative critical Si/PE size to repel all the incident ions is around 1.1 × 1.1 cm2/2.5 × 2.5 cm2. The potential of the secondary electron suppressor has been varied from -500 V to +500 V. It changes the secondary electron distribution around the implanted area and, consequently, affects the accumulation of charges at the sample surface. When the potential is 0 V, a uniform ion implantation with little effect of charge accumulation for all sizes of PE coupons is obtained. A two-dimension model has been performed and gives a good explanation for the mechanism of the electric charge neutralisation.
- Publication:
-
Nuclear Instruments and Methods in Physics Research B
- Pub Date:
- April 2005
- DOI:
- 10.1016/j.nimb.2004.12.071
- Bibcode:
- 2005NIMPB.230..386Y
- Keywords:
-
- Ion implantation;
- Insulators;
- Electric charge accumulation;
- Low energy;
- Hydrogen;
- Polymers;
- ERD depth profiles;
- 61.80.Jh;
- 61.82.Ms;
- 61.72.Ww;
- Ion radiation effects;
- Insulators;
- Doping and impurity implantation in other materials