P-H bonds in the surface unit cell of P-rich ordered InP(001) grown by metalorganic chemical vapor deposition

摘要

The Fourier transform infrared spectrum of the MOCVD-grown (metalorganic chemical vapor deposition) P-rich ordered InP(001) surface was measured in ultrahigh vacuum applying attenuated total reflection. The surface was measured without carrying out any post-transfer surface preparation. The low-energy electron defraction pattern showed the well-known (2 X 1) structure with streaks in the [-110] direction. After exposure to activated deuterium, the different infrared spectrum revealed a pronounced peak at 2308 cm~(-1), which was ascribed to P-H bonds. Polarization-dependent spectra showed the dipole moments of the P-H bonds oriented only in [001] and [-110] directions. A weak 0.8 cm~(-1) splitting was measured between the symmetric and antisymmetric modes of two neighboring P-H bonds. These observations provide direct proof for two oriented P-H bonds as in the surface unit cell proposed by Hahn and Schmidt [Surf. Rev. Lett. 10, 163 (2003)]. Additional much smaller peaks with different polarization behavior varied greatly for different samples and were ascribed to defects or impurities.