ANNEALING OF DAMAGE-INDUCED DEEP LEVELS IN MEV SI-IMPLANTED GAAS

Structural and electrical characteristics of MeV Si ion-implanted and thermally-annealed GaAs samples are reported. The annealing behavior of strain depth profiles is correlated with the annealing behavior of implant-induced defects. The depth profiles of carrier concentration and mobility were obtained by van der Pauw Hall measurements and successive layer removal by chemical etching. The concentration depth profiles suggest defect-assisted diffusion of the dopants and the mobility profile shows a broad minimum due to the residual damage. Deep level transient spectroscopy (DLTS) measurements revealed two electron traps at E(c) -0.59 eV and at E(c) -0.83 eV in the implanted region. An almost complete removal of both traps was observed after a rapid thermal annealing (RTA) at 950-degrees-C and an additional furnace annealing at 750-degrees-C. It is suggested that As(Ga) antisite defects are involved in both traps. The I-V-T measurements show a large leakage current in the diodes made in the high-trap-density region of an RTA-annealed sample. This large leakage current is shown to be caused by the trap-assisted tunneling process in the Schottky junction.