Lateral Spreads of Be and Si in GaAs Implanted with a Maskless Ion Implantation System

Abstract

Submicron Si and Be ion beams have been implanted into GaAs using a 100 kV maskless ion implantation system with a liquid metal ion source which is capable of emitting double ion species (Si⁺⁺ and Be⁺⁺). Both ion beams are implanted at 160 keV with the dose of 10¹² to 10¹⁵ cm^-2. The profiles of the implanted dopants have been estimated by observing the stain etching patterns on the cleaved planes before and after annealing. It has been found that high dose implantation results in a considerable lateral impurity spread of 1 µm or more, even with the focused ion beams having a diameter of 0.1 µm. However, doping of submicron width can be realized with relatively low doses or with shallow implantation.