The piezoelectric photo-thermal (PPT) and the surface photo-voltage (SPV) spectra of GaAs/AlAs short-period superlattices (SPS)confined GaAs single-quantum well (SQW) were measured. The electron nonradiative transitions within GaAs-SQW and subband of SPS were observed in the room-temperature PPT spectrum. At low temperature (81 K), the PPT and SPV peaks originated from the exciton transition of el-hhl and el-lhl within GaAs-SQW were observed. These peak intensities showed the opposite behavior followed by a photo-quenching (PQ) of EL2 existing in GaAs substrate. It was found that EL2 in the substrate exerted an influence on the carrier transition mechanisms within GaAs-SQW and the electron nonradiative paths through EL2 were clearly discussed by the PPT and SPV measurements. (C) 2007 Elsevier Ltd. All rights reserved.