Drift velocity of electrons in quantum wells of selectively doped In0.5Ga0.5As/Al x In1 − x As and In0.2Ga0.8As/Al x Ga1 − x As heterostructures in high electric fields

Abstract

The field dependence of drift velocity of electrons in quantum wells of selectively doped In0.5Ga0.5As/AlxIn1 − xAs and In0.2Ga0.8As/AlxGa1 − xAs heterostructures is calculated by the Monte Carlo method. The influence of varying the molar fraction of Al in the composition of the AlxGa1 − xAs and AlxIn1 − xAs barriers of the quantum well on the mobility and drift velocity of electrons in high electric fields is studied. It is shown that the electron mobility rises as the fraction x of Al in the barrier composition is decreased. The maximum mobility in the In0.5Ga0.5As/In0.8Al0.2As quantum wells exceeds the mobility in a bulk material by a factor of 3. An increase in fraction x of Al in the barrier leads to an increase in the threshold field Eth of intervalley transfer (the Gunn effect). The threshold field is Eth = 16 kV/cm in the In0.5Ga0.5As/Al0.5In0.5As heterostructures and Eth = 10 kV/cm in the In0.2Ga0.8As/Al0.3Ga0.7As heterostructures. In the heterostructures with the lowest electron mobility, Eth = 2–3 kV/cm, which is lower than Eth = 4 kV/cm in bulk InGaAs.