Atomic hydrogen cleaning of polar III–V semiconductor surfaces

Abstract

Atomic hydrogen (H*) generated by a simple thermal cracker source has been used to efficiently clean the polar surfaces of several III–V semiconductors at temperatures significantly lower than those normally required for oxide desorption. The process of atomic hydrogen cleaning (AHC) is demonstrated for the preparation of the (001) and (111)A surfaces of InAs, and the InSb(001) and GaSb(001) surfaces. Both the substrate anneal temperature and the required H* dose vary for the different materials, but in all cases clean, well-ordered surfaces can be produced, as determined by low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). It is found that both the InAs and GaSb surfaces can be cleaned with H* exposures at a specific temperature (as low as 470 K for GaSb and 700 K for InAs); however, for InSb it is also necessary to supply an Sb 4 flux from a Knudsen cell to avoid decomposition of the surface. High resolution electron energy loss spectroscopy (HREELS) has been used to monitor the surface plasmon excitations in these doped materials to measure the carrier concentration in the near-surface region. It is found that no measurable passivation of donors or acceptors occurs in either the n-type or p-type materials studied. In addition, and in contrast to ion sputtering procedures, no defect induced increase in the carrier concentration occurs as a result of atomic hydrogen cleaning.