Photoluminescence transients due to hole capture at DX centers in ${\mathrm{Al}}_{\mathrm{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathrm{x}}$As:Si

The near-band-gap photoluminescence of AlGaAs:Si shows a slow intensity transient after cooling the sample in darkness to low temperatures. This transient correlates to the Si dopant concentration. By investigating the behavior for below- and above-band-gap illumination we show that the observed transients are caused by hole capture at the DX center (hole-capture cross section ${\mathrm{\delta }}_{\mathrm{DX}}$,h≥2×${10}^{\mathrm{-}16}$ ${\mathrm{cm}}^2$). Using the transient to determine the occupation of the DX state, we confirm the electron-capture barrier and the photoionization cross section for DX centers, observed by Mooney et al.