Raman scattering investigations of molecular beam epitaxy n-type gallium-arsenide surfaces

Raman light scattering has been utilized to investigate the surface properties of single crystal molecular beam epitaxy (MBE) grown {dollar}langle{dollar}100{dollar}rangle{dollar} n-type GaAs. Surface characteristics of the samples modified by reactive ion etching (RIE) in a low pressure multipolar reactor and those modified by chemical etching have been studied by Raman spectroscopy at room temperature. The effect of rapid thermal annealing (RTA) on GaAs surfaces following argon etching and RIE at high ion energies has also been studied. Electrical measurements of Schottky diodes have been compared to the Raman studies of lightly Si-doped GaAs.; Room temperature Raman spectra were obtained in a backscattering geometry from the {dollar}langle{dollar}100{dollar}rangle{dollar} surface of the GaAs samples. Based on the Raman selection rules, only the longitudinal optic phonon mode is allowed for an undoped GaAs in the backscattering geometry. The longitudinal optic phonon (LO) and the coupled plasmon-LO phonon modes were observed in the Raman spectra of highly Si-doped GaAs samples with 5 {dollar}times{dollar} 10{dollar}sp{lcub}18{rcub}{dollar} cm{dollar}sp{lcub}-3{rcub}{dollar} {dollar}{dollar}200 eV was larger than the unetched samples. Specifically, the depletion width for 400 eV RIE sample was measured to be 13 {dollar}pm{dollar} 2 nm compared to 8.5 {dollar}pm{dollar} 2 nm for the unmodified surfaces.; The effect of rapid thermal annealing (RTA) was also studied by Raman scattering for a 400 eV RIE sample and a 200 eV argon (sputter) etched sample. The results indicate the possibility of arsenide atom vacancy sites on the surfaces of high energy ion etched GaAs samples that cannot be removed by annealing.; Investigation of the {dollar}langle{dollar}100{dollar}rangle{dollar} surface of n-GaAs by Raman scattering, along with the electrical characteristics of the Schottky barriers, indicate that using a low pressure multipolar reactive ion etch system at ion bombardment energies {dollar}<{dollar}200 eV allows etching without introducing any measurable surface disordering. (Abstract shortened with permission of author.)...