Semiconductor laser having an improved lateral carrier injection structure to multiple quantum well layers

摘要

The present invention also provides another semiconductor multilayer carrier injection structure in a semiconductor laser. The semiconductor multilayer carrier injection structure comprises the following elements. The semiconductor multilayer carrier injection structure includes a multiple quantum well active layer comprising alternating laminations of quantum well layers made of a first compound semiconductor having a first energy band gap and potential barrier layers made of a second compound semiconductor having a second energy band gap larger than the first energy band gap. Each of the quantum well layers has an electron ground state of quantum energy levels of electrons and a hole ground state of quantum energy levels of holes. The semiconductor multilayer carrier injection structure also includes a first carrier injection guide layer being provided in contact with a first lateral end portion of the multiple quantum well active layer. The first carrier injection guide layer is made of a third compound semiconductor of a first conductivity type. The third compound semiconductor has a third energy band gap which is larger than a difference between the electron ground state and the hole ground state of the quantum well layers and which is smaller than the second energy band gap of the potential barrier layers. The semiconductor multilayer carrier injection structure also includes a second carrier injection guide layer being provided in contact with a second lateral end portion of the multiple quantum well active layer. The second carrier injection guide layer is made of a fourth compound semiconductor of a second conductivity type. The fourth compound semiconductor has a fourth energy band gap which is larger than the difference between the electron ground state and the hole ground state of the quantum well layers and substantially equal to or smaller than the second energy band gap of the potential barrier layers.