MODIFICATIONS OF SPACE-CHARGE LAYER ON INP(110) SURFACE-INDUCED BY ATOMIC-HYDROGEN AT VERY-LOW EXPOSURES

The HREEL spectrum of InP(110) in the quasi-elastic peak region is str ongly modified by the exposure to atomic hydrogen. From a detailed ana lysis of these modifications we have shown that (i) cleavage induced s tates in InP can have acceptor-like nature, as an ''unavoidable'' smal l upwards band bending was always present even on mirror-like cleaved surfaces; (ii) atomic hydrogen at very low exposures can neutralize th ese acceptor states, reducing to almost zero the pre-existing band ben ding; (iii) at high exposures, H induces new acceptor states inside th e gap and, consequently, a new and larger band bending occurs at the s urface, which reaches about 0.6 eV above 10(3) L.