A GENERAL-APPROACH TO MEASUREMENT OF BAND OFFSETS OF NEAR-GAAS ALLOYS

Band offsets can be found by high-pressure spectroscopy if the X-minim a of a heterostructure are type II. However, many heterostructure syst ems do not have a type II X-minimum and then this method does not work . We therefore propose a new approach to measuring band offsets. It is capable of obtaining the band offsets of any near-GaAs alloy against GaAs by comparing the photoluminescence energies of alloy and GaAs qua ntum wells with AlGaAs barriers below and above crossover. The method is demonstrated for the case of InGaAs. There are other candidate syst ems which mag usefully be used in the same manner as GaAs/AlGaAs. Befo re they can be used it is necessary to check whether the X-minimum is type II or not. We present data confirming that the GaInP/GaAs system also has a type II X-minimum and can therefore also be used.