Patent ID: 7889773
Filing Date: 2011-02-15
Classification: B82Y,G02F,H01S

Abstract:
1. A semiconductor device, comprising: an InP substrate; a first semiconductor layer made from Al a second semiconductor layer made from Al a third semiconductor layer made from In a fourth semiconductor layer made from In said first, second, third and fourth semiconductor layers are provided in order in a contacting relationship with each other over said InP substrate; said first and second semiconductor layers have compositions which are same as or substantially same as each other on an interface therebetween; the composition of said second semiconductor layer continuously varies such that a band gap continuously increases from the first semiconductor layer side toward the third semiconductor layer side; the compositions of said second and third semiconductor layers are set such that energy levels of a valence band maximum are equal to or substantially equal to each other on an interface between said second and third semiconductor layers; the composition of said third semiconductor layer continuously varies such that a band gap continuously increases from the second semiconductor layer side toward the fourth semiconductor layer side; and the compositions of said third and fourth semiconductor layers are same as or substantially same as each other on an interface between said third and fourth layers.