ATOMIC-HYDROGEN CLEANING OF POLAR III-V SEMICONDUCTOR SURFACES

Atomic hydrogen (H) generated by a simple thermal cracker source has been used to efficiently clean the polar surfaces of several III-V sem iconductors at temperatures significantly lower than those normally re quired for oxide desorption. The process of atomic hydrogen cleaning ( AHC) is demonstrated for the preparation of the (001) and (111)A surfa ces of InAs, and the InSb(001) and GaSb(001) surfaces. Both the substr ate anneal temperature and the required H dose vary for the different materials, but in all cases clean, well-ordered surfaces can be produ ced, as determined by low energy electron diffraction (LEED) and Auger electron spectroscopy (AES). It is found that both the InAs and GaSb surfaces carl 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, flux from a Knudsen cell to avoid deco mposition of the surface. High resolution electron energy loss spectro scopy (HREELS) has been used to monitor the surface plasmon excitation s in these doped materials to measure the carrier concentration in the near-surface region. It is found that no measurable passivation of do nors or accepters occurs in either the n-type or p-type materials stud ied. In addition, and in contrast to ion sputtering procedures, no def ect induced increase in the carrier concentration occurs as a result o f atomic hydrogen cleaning. (C) 1998 Elsevier Science B.V. All rights reserved.