Electronic properties of dilute Bismide alloys*

The alloying of GaAs with small amounts of N or Bi results in a large reduction of the fundamental band gap, leading to the so called ``giant band gap bowing''. GaAs$_{1-x}$N$_{x }$has been the subject of intense investigation in recent years; however the lower mobility of the dilute nitride alloys limits its use for device applications. Bi incorporation is predicted to mainly perturb the valence band and does not significantly affect the electron mobility, thus promising better device performance. We report photoluminescence (PL) measurements of GaAs$_{1-x}$Bi$_{x}$ epilayers grown by MBE, carried about at different temperatures (4 - 300K), with above-band gap and selective excitation. Time-resolved PL measurements were also carried out to study the carrier lifetimes of the Bi-related states in these samples.