Ion-implanted GaAs for subpicosecond optoelectronic applications

Ion implantation is shown to be able to shorten the carrier lifetime in semi-insulating GaAs independent of the ion species. Although ion implantation alone may shorten the lifetime to the order of femtoseconds, to obtain good resistivity and mobility an annealing process is required. Furthermore, chemically active ions may complicate the recovery of resistivity, such as Si which may be activated as dopants during annealing or O which creates additional deep levels. Optimum annealing temperature was determined to be around 600/spl deg/C with carrier lifetime still in the picosecond range but with mobility /spl sim/2000 cm/sup 2/V.s. The shortening of the carrier lifetimes and electrical properties of these materials are correlated to the structural properties.