Differential surface photovoltage spectroscopy of δ‐doped GaAs/AlAs multiple quantum wells below and close to Mott transition

Abstract

Differential surface photovoltage (DSPV) spectra of Be δ‐doped GaAs/AlAs multiple quantum wells (MQWs) with doping densities below (5 × 1010 cm–2) and near (5 × 1012 cm–2) a Mott transition were studied at 300 K and 90 K. From the line shape analysis of the DSPV spectra, exhibiting obvious doping and temperature dependences, an origin of optical transitions has been revealed. The spectra of lightly doped structures were accounted for by ground state heavy and light‐hole related excitonic transitions. In highly doped GaAs/AlAs MQWs the heavy‐hole excitons were found to be quenched while rather broadened light‐hole related transitions still exhibited an excitonic character. The experimental observations suggest that with increasing doping level phase‐space filling effects dominate over Coulomb screening. The renormalization effects due to many body interactions were found to be more pronounced for the lowest heavy‐hole subband when compared to the light‐hole one. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Low-frequency noise properties of beryllium δ-doped GaAs/AlAs quantum wells near the Mott transition

“…25 Application of modulation spectroscopy has allowed estimation of internal built-in electric fields and broadening mechanisms, 26 discrimination between the origin of optical transitions below and close to the Mott transition, and demonstration that with increasing doping level phase space filling effects dominate over the Coulomb screening. 27 Photoluminescence (PL) and time-resolved PL spectra studies have also demonstrated acceptor-impurity induced effects in the (PL) line shapes dependent on the QW widths 28 and allowed one to investigate possible mechanisms for the carrier radiative recombination, both above and below the Mott metal-insulator transition. 29 In this work, we complement this family of experimental techniques by showing that low-frequency noise measurements are useful method to extract a large variety of information investigating beryllium d-doped GaAs/AlAs QWs.…”