Blistering of GaAs by low keV H, D, and He ions

The thermally activated blistering of the GaAs (100) surface after 5- and 10keV H, D, and He ion implantations was investigated. A large isotope effect is observed as the critical blistering fluences are two to three times higher for D than for H ions. Blistering and exfoliation are also obtained for very low He ion fluence, contrary to Si which is impervious to He blistering in the same conditions. The exfoliated crater depth depends strongly on the He fluence, varying, at 10keV, from 75±10nm (for 1.6×1016He∕cm2), consistent with the ion projected range determined by computation, to a saturation value of 155±10nm for doses >4×1016He∕cm2. Our results suggest that the fracture leading to cleavage is triggered at a local He concentration of about 2at.%, where dislocations and nanocavities are created.