Photoluminescence of pre-growth treatment induced below-bandgap states in GaAs

Below-bandgap states induced by pre-epitaxial growth treatments in semi-insulating (s.i.) GaAs has previously been investigated by photoluminescence (PL). Various electronic states giving rise to near-infrared PL peaks are generated through processes such as annealing or buffer growth that are standard for epitaxial growth of InAlGaAs structures on (001) GaAs substrates. These states often overlap with those from InGaAs structures, not only complicating the interpretation but also altering the electronic properties of the devices. The present study extends the investigation to the case of doped n- and p-type (001) GaAs substrates. These substrates are widely utilized in various optoelectronic applications, and therefore information on below bandgap states are important to distinguish the desired electronic states from the pre-growth treatment-induced defect states. It was found that the behavior of n- and p-type substrates subjected to pre-growth treatment are different from that of s.i. GaAs.