LVM spectroscopy of carbon and carbon-hydrogen pairs in GaAs grown by MOMBE

Abstract

Cryogenic (4.2 K) infrared absorption measurements of GaAs films grown by MOMBE and containing a high concentration of carbon acceptors ( approximately 2*1020 cm-3) show an asymmetric Fano resonance at the frequency of the CAs local mode (582 cm-1). After rapid transient annealing at 950 degrees C for 12 s in an atmosphere of helium and arsine, there is a reduction in the hole concentration, and localized vibrational mode (LVM) spectroscopy reveals the presence of nearest neighbour H-CAs passivated pairs. Previously unreported lines at 452.8 cm-1 and 563.0 cm-1 may be due to the vibrations of the passivated carbon atoms, or possibly CGa donors.