We present a study of type II interfaces between semiconducting materials. In this type of interface the lineup of the two semiconductor band gaps has a staggered shape. The band bending at the interface depends on the doping type and concentration of the two semiconductors involved. In most cases two triangular quantum wells appear at the interface, one for the electrons in the semiconductor having the lowest conduction band edge and one in the other material for holes. In such a case, when charges are injected, the electrons and holes are separated at the interface, so that the electron/hole recombination occurs through the interface. The main characteristic of type II interfaces is that their photoluminescent (PL) intensity is very high compared with each material forming the heterojunction. This high PL intensity can be used advantageously in optoelectronic device applications. We present semiconductor pairs for which it is possible to have type II interfaces and their optical properties. We will emphasize particularly the cases of AlInAs/InP and GaPSb/InP whose low-temperature interface recombination energies are 1.2 and 0.90 eV, respectively.
Polarized optical properties in type-II ZnTe/CdSe multiple quantum wells induced by interface chemical bonds