N-type induced junction black silicon photodiode for UV detection

Commercial photodiodes suffer from reflection losses and different recombination losses that reduce the collection efficiency. Recently, we realized a near-ideal silicon photodiode that exhibits an external quantum efficiency above 95% over the wavelength range of 235 – 980 nm, exceeds 100% below 300nm, and provides a very high response at incident angles of up to 70 degrees. The high quantum efficiency is reached by 1) virtually eliminating front surface reflectance by forming a “black silicon” nanostructured surface having dimensions proportional to the wavelength of light to be detected and 2) using an induced junction for signal collection instead of a conventional doped p-n junction, virtually eliminating Auger recombination at the light entry surface. This recombination prevention is especially important in ultraviolet detection since ultraviolet photons are absorbed very close to device surface, where conventional photodiodes have high doping concentration causing loss of signal, but induced junction diode is able to collect virtually all charge carriers generated. In this paper, we analyse the performance of our photodiodes under ultraviolet radiation.