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 VGe. 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.