Experimental evidence for the distinction between metastability and persistence in optical and electronic properties of bulk GaAs and AlGaAs

Abstract

In this paper we present experimental evidence supporting that persistent behavior in the electronic and optical properties of bulk GaAs and AlGaAs can have di erent origins as: the metastability o f a defect, the persistent c harge transfer from a defect to another defect, and the transfer from a defect to the conduction band. In particular, we show three di erent cases in which defects are either directly or indirectly related to persistent c hanges of the optical absorption, the magnetic circular dichroism of the absorption MCDA and the photoconductivity PC . The three cases are as follows: the transfer of EL2 to the metastable state EL2 0 in semi-insulating SI GaAs causing persistent quenching of the absorption and photoconductivity PPCQ ; the persistent transfer of electrons from stable EL2 0 to arsenic vacancies in lightly n-type GaAs; and the correlated appearance of persistent MCDA and photoconductivity in AlGaAs due to the photoionization of DX-centers.

Memory effect in semiconductor gas discharge electronic devices

“…The microscopic structure of EL2 is still a controversial subject; it is accepted that its core is an arsenic antisite (AsGa) [52] acting as a double donor, it has three charge states EL2 0 , EL2 + and EL2 ++ which introduce two ionization levels in the band gap (E v + 0.75 eV for 0/+ and E v + 0.54 eV for +/++). Its neutral charge state has an excited state, EL2 0 , which is metastable and optically and electrically inactive at low temperatures [53]. The results obtained confirm the possibility of explaining the total voltage/current effect based on processes occurring mainly in the cathode ports.…”