Electrical characterization of Si+ and Si+/P+ implanted N+PIn0.53Ga0.47As junctions

In this communication, we present I-V and admittance spectroscopy measureme nts of shallow n(+)p junctions into p-InGaAs made by Si+ implantation, incl uding a complete study of the conduction mechanisms as a function of temper ature. The effect of P+ co-implantation is also analysed. The I-V character istics of both junctions show that recombination in the space-charge zone i s the dominant transport mechanism in forward bias, with ideality factors a round 1.5 at 300 K that increase with decreasing temperature of measurement . Activation energies of the reverse saturation current are obtained at roo m temperature, being 0.5 eV and 0.4 eV for Si+ and Si+/P+ implanted diodes, respectively, indicating that recombination currents occur through a near midgap center. Reverse current-voltage measurements show a higher conductio n in the P+ co-implanted junction due to a higher concentration of traps. I n both types of junctions, the reverse characteristics can be fitted to a t hermally-activated trap-assisted tunneling mechanism at low bias, involving traps at 0.41 eV and 0.44 eV for Si+ and P+ co-implanted junctions, respec tively, whereas different trap-assisted tunneling processes dominate at med ium and high bias. The small signal analysis show a clear difference betwee n the two types of junctions. The use of Kramers-Kronig transforms on the a dmittance spectroscopy data reveals the presence of a defect level at 0.35 eV in both types of junctions, probably assigned to Zn, the native acceptor present in the p-InGaAs. Another trap level at 0.30 eV is detected at the P+ co-implanted junctions, not appearing in the Si doped junctions, which c ould probably be due to damage produced by the co-implantation.