High-rate deposition technique of hydrogenated microcrystalline silicon (µc-Si:H) light absorber is essentially required for low cost manufacturing of silicon-based thin film solar cells. We have developed a high-rate plasma process based on SiH₄-H₂ glow discharge for highly efficient µc-Si:H p-i-n junction solar cells. In high-deposition-rate regime (2-3 nm/s), we observed a remarkable improvement in visible-infrared responses upon increasing deposition pressure (up to 7-9 Torr) under SiH₄-depletion plasma condition, yielding high short circuit current. As a result, a maximum efficiency of 9.13% has been achieved at a deposition rate of 2.3 nm/s. We attribute the improved photovoltaic performance of high-pressure-grown µc-Si:H to the structural evolution toward denser grain arrangement that prevents atmospheric impurity diffusion and post-oxidation of grain boundaries.