Heterojunction diodes nGaAs/pSi with ideal characteristics

Heterojunction (HJ) diodes nGaAs/pSi have been fabricated from GaAs-on-Si heterostructures grown by molecular beam epitaxy and exhibited surprisingly ideal characteristics, despite the high density of misfit dislocations in the GaAs/Si interface. For n approximate to p approximate to 10(16) cm(-3) an ideality factor, n, of 1.06 was determined from I-V measurements at 300 K while an intercept voltage V-int = 0.82 V was obtained from 1/C-2-V plots, approaching closely the 0.82 V value predicted for the junction's built-in voltage according to Anderson's model (Delta E(v) = 0.32, eV and Delta E(c) = 0.02 eV; Delta E(c) equals the difference in GaAs and Si electron affinity values). HJ diodes with n = 8 X 10(16) cm(-3) and p = 7 X 10(14) cm(-3) were also grown on cm vicinal (100) substrates with various tilting angles (0-9 degrees) and prelayer conditions. They all exhibited almost the same V-int = 0.68 V, while n varied between 1.13-1.26, being best for the GaAs/Si heterostructure which exhibited the lowest threading dislocation density. The results are encouraging for the incorporation of GaAs/Si heterojunctions into real device Structures.