Electron scattering in GaAs/n‐AlGaAs selectively doped heterojunctions with charged and neutral InGaAs quantum dots

Abstract

The scattering process of electrons has been studied in selectively doped GaAs/n-AlGaAs inverted heterojunctions, where InGaAs dots are embedded in the vicinity of a GaAs channel. By performing both capacitance and Hall measurements, the percentage Poc of charged dots filled with an electron is determined as a function of the gate voltage Vg and is found to vary from about 30% to 90% with Vg. We have also examined both mobilities μ and the ratio of the quantum lifetime τq to the transport lifetime τt of electrons. It is found that μ increases with Vg(Poc), suggesting that the scattering by a charged dot is weaker than that by a neutral dot. It is also found that the ratio τq/τt decreases with Vg(Poc), indicating that the scattering potential associated with a charged dot is of a longer range as compared with the scattering by a neutral dot.