Photoluminescence of InAs1−xSbx/AlSb single quantum wells: Transition from type-II to type-I band alignment

Infrared photoluminescence has been used to study the band-gap energy of InAs1−xSbx digital superlattices and band alignment of InAs1−xSbx/AlSb quantum wells at 5 K. It is found that the InAs1−xSbx digital alloys have a smaller effective band gap than InAs1−xSbx random alloys. In addition, the valence band offset between type-II InAs/AlSb is determined to be 130 meV. This number reduces as the Sb mole fraction in InAs1−xSbx is increased, and the alignment between InAs1−xSbx/AlSb becomes type I when x>0.15.