Analyses of GaN (0 0 0 1) and ( 0 0 0 1 ¯ ) surfaces by highly-charged ions

Secondary-ion mass spectroscopic studies for wurtzite GaN (0 0 0 1) and ( 0 0 0 1 ¯ ) surfaces grown by hydride-vapor phase epitaxy were carried out using highly-charged ions. The secondary ions of impurities adsorbed on the surfaces, such as proton, H 2 + , and C m H n + ( m = 1–6 and n = 0–13), were preferentially desorbed by the grazing incidence of Ar q+ ( q = 6–11). A spectrum peak of Ga + was observed only in the (0 0 0 1) surface, whereas an enhancement of the peak intensity of N + was observed in the ( 0 0 0 1 ¯ ) surfaces. The time difference between the two peaks was also observed in the time-of-flight spectra of protons emitted from the (0 0 0 1) and ( 0 0 0 1 ¯ ) surfaces. It was concluded that these differences were due to the surface polarity of GaN.