A low-resistance spiking-free n-type ohmic contact for InP membrane devices

Au spiking is a long-standing problem for Ni/Ge/Au ohmic contacts on n-InP. This becomes more critical when the contacts are deposited on top of thin membrane devices. In order to reduce the spiking while maintaining a low resistance, we present a new approach which reduces the amount of Au in these contacts. A low specific contact resistance of 7×10^-7 Ωcm² is obtained after a 15 s annealing at 400 °C. Afterwards the contacts can be thickened with an extra deposition of metals. Scanning electron microscope pictures show abrupt and uniform interfaces between metals and semiconductors.