Effects of point defect healing on phosphorus implanted germanium n ⁺/p junction and its thermal stability

In this work, the effect of Ge point defect healing process between 550 °C and 650 °C is investigated, in the aspect of leakage (off) current and junction depth of Ge n⁺/p junction diodes using ECV, TEM, J-V, and SIMS analyses. After 600 °C anneal, off-current density (2 × 10^-4 A/cm²) is dramatically reduced due to the defect healing phenomenon that decreases the number of point defects, subsequently providing a higher on/off-current ratio of 5 × 10³. In spite of the high healing temperature, junction diodes seem not to suffer from the deep diffusion of phosphorus (P) in Ge because those diffuse mostly through V _Ge. In addition, it is also confirmed that Ti is an appropriate material in terms of diffusion barrier and diffusivity for Ge n⁺/p junction contact metal.