Abstract
This thesis reports an investigation into the nature of the compensation introduced when oxygen is implanted into n-type gallium arsenide. Results have been obtained using Hall effect and capacitance voltage measurements with computer simulation being applied to both techniques to assess the errors encountered when measuring ion implanted material. Notably, the effect of the air semiconductor depletion region on Hall effect measurements has been shown to lead to large discrepancies between the two techniques. The simulation has enabled the two measurements to be harmonised and estimates have been made to profile shapes in the depletion region, an area which was previously immeasurable. After simulation the results show that the behaviour of oxygen is dependant on the original species of n-type dopant used. Silicon, selenium and sulphur implants have been studied. The results show that the compensation introduced by oxygen implantation is dominated by damage related mechanisms. The damage mechanism is shown to depend on the original n-type dopant used. Deep silicon implants show that there is a definite contribution from centres which require the presence of the oxygen atom. The conclusion of the work is that the nature of the compensation introduced by oxygen is complex but is possibly linked to local fluctuations in stoichiometry which inhibit the activation on the gallium site.