Se+ ion implantation into encapsulated GaAs

PECVD Si3N4 was deposited on undoped SI (100) GaAs. Se+ ions were implanted with a dose of 1×1014 ions cm¿2 at an ion energy of 400 keV through the Si3N4 layer. Annealing was carried out on a dual graphite strip heater at temperatures up to 900°C for 100 s. Transmission electron microscope studies show a large concentration of damage in the form of dense dislocation tangles and long-range strain centres at the Si3N4/GaAs interface. Below this sheet of gross damage the material contains a relatively low density of dislocation loops. Electrical measurements indicate that, for a similar implant condition directly into GaAs, a relatively high electrical activity is measured compared with that of the implants through the Si3N4 encapsulating layer.