Dark-current analysis of InGaAs-MSM-photodetectors on silicon substrates

We fabricated In_0.53Ga_0.47As metal-semiconductor-metal (MSM) photodetectors on lattice-mismatched (001)Si substrates in order to analyze the influence of lattice defects on the III-V semiconductor device properties. The growth procedure and the device-fabrication process are described. The low native Schottky-barrier of InGaAs is enhanced by a p⁺n-InP double layer. Dark-current densities in the operation range measured with the lattice-mismatched devices are comparable to those of lattice-matched devices on InP. Their statistical distribution proves the good reproducibility of the fabrication process. From the temperature and voltage dependence of the dark current, we find that on Si the current in the medium voltage range is obviously influenced by defect-related centres in the bandgap. An empirical model is presented to describe the experimental findings. The dark current is low enough for applications of the MSM detectors in optoelectronic systems