Defect Repair and Dopant Activation in Boron‐Implanted Germanium Through Integrated Microwave and Supercritical Fluid Treatment

In this work, we demonstrate a low‐thermal‐budget two‐step annealing strategy that integrates microwave annealing (MWA) and supercritical fluid (SCF) treatment to optimize the electrical and structural properties of boron (B)‐implanted Ge substrates. In the first step, MWA enables rapid defect recovery while promoting dopant activation. The subsequent pressure‐controlled CO ₂ treatment further modifies the structural and electrical characteristics of the implanted Ge. Electrical characterization reveals that the most favorable 50 atm treatment reduces the sheet resistance from 49.24 to 25.571 Ω/sq. and increases the Hall mobility from 80.1 to 118 cm ²  V ⁻¹  s ⁻¹ compared with MWA‐only treatment. Structural analyses using Raman spectroscopy and transmission electron microscopy indicate improved crystalline quality and reduced implantation‐induced damage under the most favorable investigated treatment condition. This combined MWA–SCF process improves dopant activation and defect recovery under a relatively low additional thermal budget and provides a promising route for advanced Ge‐based device processing.