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 nGaAs/pSi interface. For n ≈ p ≈ 1016 cm−3 an ideality factor, n, of 1.06 was determined from I-V measurements at 300 K while an intercept voltage Vint = 0.82 V was obtained from 1C2-V plots, approaching closely the 0.82 V value predicted for the junctionʹs built-in voltage according to Andersonʹs model (ΔEv = 0.32 eV and ΔEc = 0.02 eV; ΔEc equals the difference in GaAs and Si electron affinity values). HJ diodes with n = 8 × 1016 cm−3 and p = 7 × 1014 cm−3 were also grown on vicinal (100) substrates with various tilting angles (0–9°) and prelayer conditions. They all exhibited almost the same Vint = 0.68 V, while n varied between 1.13–1.26, being best for the nGaAs/pSi heterostructure which exhibited the lowest threading dislocation density. The results are encouraging for the incorporation of nGaAs/pSi heterojunctions into real device structures.