Energy band discontinuities in heterojunctions measured by internal photoemission

A novel method involving internal photoemission has been developed to determine the conduction band discontinuity Δ Ec of heterojunctions. The method is straightforward, accurate, and assumes minimum unknowns; and has been applied to GaAs/AlxGa1-xAs heterojunctions. We have found for x<0.4 that Δ Ec≅0.62 Δ Eg, where Δ Eg is the band-gap difference. For x>0.4, the apparent Δ Ec is considerably smaller.