Reduction of electron accumulation at InN(0001) surfaces via saturation of surface states by potassium and oxygen as donor- or acceptor-type adsorbates

Abstract

The influence of selected donor- and acceptor-type adsorbates on the electronic properties of InN(0001) surfaces is investigated implementing in-situ photoelectron spectroscopy. The changes in work function, surface band alignment, and chemical bond configurations are characterized during deposition of potassium and exposure to oxygen. Although an expected opponent charge transfer characteristic is observed with potassium donating its free electron to InN, while dissociated oxygen species extract partial charge from the substrate, a reduction of the surface electron accumulation occurs in both cases. This observation can be explained by adsorbate-induced saturation of free dangling bonds at the InN resulting in the disappearance of surface states, which initially pin the Fermi level and induce downward band bending.

Synchrotron radiation photoemission study of the ultrathin Cs/InN interface

“…Similar data concerning the induced surface band near the E VBM were found for K adsorption on the InN(0001) [26]. Note that the Cs/InN interface owing to photoemission tail near the E VBM can be considered as metallic-like interface (Figs.…”

“…For the InN(0001), the surface states were found at the energies of 0.2 eV and 0.7 eV below the E F while for InN(000 À 1), (1 À 100) and (11 À 20) surfaces the surface state is located near the E VBM [26,27]. Experimental data are in good agreement with theoretical calculations for the InN surface in various orientations [13].…”

“…The In 4d core level peak is shifted slightly to lower binding energy and reduced in intensity under increasing Cs coverage. Analogous shift to the lower binding energy was obtained for the In 4d photoemission peak due to K adsorption on the InN(0001) surface [26].…”

“…For III nitrides, accumulation layers were revealed at the clean InN surface [23,24] and formed via adsorption at both the GaN and AlGaN surfaces [28,29]. Adsorption of alkali metals Cs, K on the InN surface has been recently investigated in [21,26,27] in which the significant modification of the surface electronic structure has been demonstrated. For the K/InN interface, a reduction of surface accumulation and the disappearance of surface states are observed [26].…”

“…Adsorption of alkali metals Cs, K on the InN surface has been recently investigated in [21,26,27] in which the significant modification of the surface electronic structure has been demonstrated. For the K/InN interface, a reduction of surface accumulation and the disappearance of surface states are observed [26].…”