Germanium n+/p Shallow Junction With Record Rectification Ratio Formed by Low-Temperature Preannealing and Excimer Laser Annealing

A germanium n+/p shallow junction formed by a combination of low-temperature preannealing (LTPA) and excimer laser annealing at a low fluence of 150 mJ/cm2for phosphorus-implanted germanium is demonstrated. The LTPA step plays a critical role in annihilating the implantation damages and significantly suppressing phosphorus diffusion during laser annealing process, resulting in a very small dopant diffusion length with high activation level of phosphorus. A well-behaved Ge n+/p shallow junction diode with a record rectification ratio of\(~ 10⁷\)and low leakage current density of\(8.3 × 10⁻⁵\)A/cm2is achieved, which is greatly beneficial to the scaled Ge MOSFET technology.