The structural and electrical properties of low‐resistance Ni contacts to InP

We have investigated the electrical and metallurgical behavior of the Ni‐InP contact system. Specific contact resistivity (Rc) values in the low 10−7 Ω cm2 range are achieved with Ni‐only contacts on n‐InP (Si: 1.7×1018 cm−3) by sintering at 400 °C for several minutes. The post‐sinter contact metallization consists of three layers, arranged in the sequence: InP/Ni3P/Ni2P/In. Extended sintering (40 min) at 400 °C brings about a rise in Rc to the 10−4 Ω cm2 range. After extended sintering, the contact metallization is found to consist of only two layers, arranged in the sequence: InP/Ni2P/In. Based on the correlation between low Rc and the presence of Ni3P at the metal‐InP interface, it is suggested that the presence of Ni3P is the cause of the low Rc values. We show that the sintering schedule used to achieve low values of Rc is accompanied by substantial metal‐InP interdiffusion that results in severe device degradation. We show, finally, that it is possible to achieve low values of Rc without incurring t...