Abstract
For detect the light wavelength of near UV and visible spectral range in application of high speed optical communication system, signal process and measurement system, the usual using semiconductors martial were GaAs or Si. But the commercially Si photodiodes are not suitable for high speed operate, because of the relatively low absorption coefficient of indirect band gap. For high speed operation must sacrifice the efficiency and bias condition. On the other hand, photodiodes using a GaAs direct band gap martial are expected to combine both high speed and high efficient at low bias voltage. But for typical GaAs PIN photodiodes, the sensitivity decrease rapid in the blue spectral region because of the high surface recombination rate of reveal windows layer surface. In this article we fabricate a newly InGaP/GaAs PIN photodiodes that are designed to have enhanced sensitivity in blue spectral region by proper choice the thickness and composition of windows layer.