Determination of the conduction-band discontinuity between in _0.53ga_0.47as/in_0.52al_0.48as using n⁺-ingaas/inalas/n^--ingaas capacitors

The conduction-band discontinuity (ΔEc) between In 0.53Ga0.47As and In0.52Al0.48As is determined by current-voltage measurements on n+-InGaAs/InAlAs/n --InGaAs capacitors. Current is found to be dominated by thermionic emission conduction down to 180 K. Barrier heights are determined from the slope of ln(J/T2) vs 1/T where good straight-line fits are obtained in the thermionic emission range. After correcting for the Fermi level a conduction-band discontinuity of 0.51±0.04 eV is obtained representing 70% of the total band-gap discontinuity. Furthermore, capacitance-voltage measurements are fit to classical capacitance-voltage theory and show that no charge is present in the InAlAs insulating layer.