The effect of GaP in Al-free, GaAs-based resonant tunnelling diodes

We have studied the role of GaP intermediate layers in GaInP/GaAs double barrier resonant tunnelling structures. Measurements of the current-voltage characteristics show an asymmetric behaviour which was improved in diodes including thicker GaP intermediate layers. From cross-sectional transmission electron microscopy investigations we have observed a fluctuation in the thickness of the GaP layers at the GaInP to GaAs transition to which we attribute the asymmetric characteristics. Finally, we demonstrate a simplified structure using only GaP layers as barriers. These new diodes show more symmetric I-V characteristics than the GaInP/GaAs tunnelling diodes.