Photodiodes are semiconductors that generate a current or voltage when illuminated by light. They have no internal gain, but can operate at much higher light levels than other detectors. Hamamatsu Si photodiodes have low capacitance and dark current, which reduces noise and increases speed. Our UV photodiodes resist degradation in performance that results from continuous exposure to ultraviolet light. Si photodiodes are suitable for precision photometry, making them useful in medical instrumentation, analytical instruments, semiconductor tools and industrial measurement systems. We also welcome enquiries for custom designed photodiodes.