Effect of doping on electron traps in metalorganic molecular-beam epitaxial GaxIn1−xP/GaAs heterostructures

Abstract
The formation of trap centers in GaxIn1−xP/GaAs epitaxial layers grown by metal‐organic molecular‐beam epitaxy (MOMBE) is investigated by deep‐level transient spectroscopy (DLTS). The undoped epitaxial layers are characterized by a deep electron trap with an activation energy that depends on the Ga mole fraction and takes values in the range 820 to 875 meV. This trap center is suppressed by S and Si doping, and a new trap at 300–345 meV appears in the doped samples with a capture cross section of 1×10−13–2×10−15 cm2, while the trap concentration increases with the dopant concentration. Persistent photoconductivity (PPC), which is present in all samples investigated, appears to be suppressed only by Si doping.