Photoluminescence and photoconductivity spectra as a function of photoexcitation density in a GaAlAs/GaAs quantum well

Photoconductivity (PC) spectra and photoluminescence (PL) spectra in a 30 nm-thick GaAlAs/GaAs quantum well have been investigated as a function of photoexcitation density. The PC spectra at 4.6–30 K showed seven fine structures above the photon energy of 1.542 eV for the ground state as well as the PC peak due to the electron-acceptor absorption in the buffer layer. The PC peaks which are characteristic to the quantum well were found to be due to the transitions from the heavy and light hole bands to the quantum levels of n=1–4 states in the conduction band. Furthermore, a broad Gaussian PC peak at 1100 nm with the half maximum of ≅300 nm was found to be due to the deep impurities. With the dual photoexcitation of an ac halogen lamp and a dc He–Ne laser, the ac PC quenching was detected by a lock-in amplifier under the dc He–Ne photoexcitation.