Junction Formation in Silicon by Positive Ion Bombardment

The effects of silicon bombardment by hydrogen, nitrogen, oxygen, neon, xenon, phosphorus and boron ions have been studied using a Van de Graaff accelerator and a 250KV Cockroft-Walton accelerator to produce ions with energies ranging from 50 kev to 1 Mev. Bombardments with each of the gaseous ions produced type conversion in p type silicon. The n type layers formed all have rather high resistivities (1 ohm or greater) with very weak n type conductivity characteristics. These junctions were apparently produced by radiation damage induced donor sites and might more appropriately be called p-i junctions. Only the phosphorus and boron bombardments have shown evidence of impurity or chemical doping effects. Post bombardment annealing has been done on the various bombarded cells with rather striking improvement in characteristics occurring in the case of the boron bombarded n type silicon blanks. It is felt that, with further effort, this technique may be quite applicable to molecular electronics and other types of semiconductor device preparation using programmed phosphorus and boron ion bombardment.