Imaging near-contact transport in the planar-collector geometry for a Schottky contact on high-purity GaAs

Variable temperature electron beam induced current (EBIC) and cathodolumine scence (CL) were combined to image electric fields and charge transport for a Schottky contact on high purity epitaxial GaAs in the planar-collector g eometry. Simultaneous EBIC and CL imaging proves that the near-contact EBIC signal is dominated by depletion effects, even in material where the bulk diffusion length greatly exceeds the intercontact distance. In forward bias , an EBIC dipole is observed, providing direct spatial indication of the tr ansition between drift and diffusion transport of locally generated charge. (C) 1999 American Institute of Physics. [S0003-6951(99)00150-3].