Highly sensitive photodetector using porous silicon

A highly sensitive photodetector was made with a metal‐porous silicon junction. The spectral response was measured for the wavelength range from 400 nm to 1.075 μm. It was demonstrated that close to unity quantum efficiency could be obtained in the wavelength range of 630–900 nm without any antireflective coating. The detector response time was about 2 ns with a 9 V reverse bias. The possible mechanisms are discussed.