Effects of p doping on GaAs/AlGaAs SAM-APDs for X-rays detection

This work focuses on avalanche photodiodes based on GaAs/AlGaAs with separated absorption and multiplication regions (SAM-APDs). The two regions are separated by a thin p-doped layer which, under the application of a reverse bias, is able to confine the potential drop only in the multiplication region. We realized such layer under the form of either a δ sheet of C atoms or a 50-nm-thick GaAs:C layer. Devices with these two structures will be discussed and compared in terms of capacitance and response to light.