Electrical characterization of Si + and Si + /P + implanted N + P + In 0.53 Ga 0.47 As junctions

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In this communication, we present I–V and admittance spectroscopy measurements of shallow n+p junctions into p-InGaAs made by Si+ implantation, including a complete study of the conduction mechanisms as a function of temperature. The effect of P+ co-implantation is also analysed. The I–V characteristics of both junctions show that recombination in the space-charge zone is the dominant transport mechanism in forward bias, with ideality factors around 1.5 at 300 K that increase with decreasing temperature of measurement. Activation energies of the reverse saturation current are obtained at room 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 conduction in the P+ co-implanted junction due to a higher concentration of traps. In both types of junctions, the reverse characteristics can be fitted to a thermally-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, respectively, whereas different trap-assisted tunneling processes dominate at medium and high bias. The small signal analysis show a clear difference between the two types of junctions. The use of Kramers–Kronig transforms on the admittance 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 could probably be due to damage produced by the co-implantation.