Si in GaN — On the Nature of the Background Donor

Abstract

AbstractA characterization of the Si impurity in GaN is performed by Raman spectroscopy. Applying hydrostatic pressure up to 25 GPa we study the behavior of the LO phonon‐plasmon mode in a series of high mobility Si doped GaN films. In contrast to earlier results on unintentionally doped bulk GaN crystals no freeze out of the free carriers could be observed in Si doped samples. We find that Si is a shallow hydrogenic donor throughout the pressure range studied. This result positively excludes Si incorporation as a dominant source of free electrons in previously studied bulk GaN samples.