High-speed,　high-efficiency　silicon　photodetectors　play　important　roles　in　the　optical　communication　links　that　are　used　increasingly　in　data　centers　to　handle　the　increasing　volumes　of　data　traffic　and　higher　bandwidths　required　as　use　of　big　data　and　cloud　computing　continues　to　grow　exponentially.　Monolithic　integration　of　the　optical　components　with　signal　processing　electronics　on　a　single　silicon　chip　is　of　paramount　importance　in　the　drive　to　reduce　costs　and　improve　performance.　Here　we　report　grating-enhanced　light　absorption　in　a　silicon　photodiode.　The　absorption　efficiency　is　determined　theoretically　to　be　as　high　as　77%　at　850　nm　for　the　optimal　structure,　which　has　a　thin　intrinsic　absorption　layer　with　a　thickness　of　220　nm.　The　fabricated　devices　demonstrate　a　high　bandwidth　of　11.3　GHz　and　improved　radio-frequency　output　power　of　more　than　14　dB,　thus　making　them　suitable　for　use　in　data　center　optical　communications.　©　2021　Optical　Society　of　America.