Investigation of the GaAs/Si heterojunction band lineup with capacitance and current versus voltage measurements

The GaAs/Si heterojunction band lineup has been investigated using capacitance versus voltage (C-V) and current versus voltage (I-V) measurements on n-GaAs/p-Si (n ≈ 1016 cm−3) heterojunction diodes. Such an approach was possible because of the fabrication of diodes with near-ideal characteristics; ideality factors of less than 1.10 were deduced from forward bias I-V measurements. The heterojunction built-in voltage was determined by extrapolation from C−2-V plots, and band offsets of ΔEC = 0.03 eV and ΔEV = 0.27 eV were calculated at 300 K for the conduction and valence bands, respectively. The heterojunction energy band diagram was constructed, I-V measurements at various temperatures in the vicinity of 300 K were used to extract the potential barrier to electron transport across the junction, and the results were consistent with those from C-V. The results also agree well with theoretical models.