Photodiode

Abstract

A photodiode includes a substrate, a rectifying layer, a buffer layer, a transition layer, an active layer, and an absorption layer. The substrate has a base lattice constant. The rectifying layer is formed on the substrate, and includes an InGaP layer, an AlGaAs layer, and an InGaAs layer which are stacked on the substrate in that order. The rectifying layer includes a connecting layer that is made of GaAs directly formed on one of the InGaP layer and the InGaAs layer. The buffer layer is made of GaAs and stacked on the rectifying layer. The transition layer is formed on the buffer layer, and includes a plurality of sub-layers that each has a lattice constant greater than the base constant but smaller than a designated constant. The active layer is formed on the transition layer and has the designated constant. The absorption layer is formed on the active layer.

Dependencies are inferred from the claim text.