TUNNELING THROUGH ULTRATHIN GAAS N(-P(++)-N(++) BARRIER GROWN BY MOLECULAR LAYER EPITAXY(+))

The I-V characteristics of ultrathin GaAs n(++)-p(++)-n(++) barrier st ructures with a 45 Angstrom thick p(++) layer grown by molecular layer epitaxy (MLE) have been measured at room temperature and 77 K. The tu nneling probability for this structure has been calculated as a functi on of effective tunneling width. It was found that good agreement betw een experiment and calculation is obtained when the effective tunnelin g width is assumed to he 75 Angstrom, which is much smaller than the d epletion width about 190 Angstrom measured by C-V method. This fact in dicates that the depletion width approximation cannot be used to measu re the exact tunneling width for ultrathin barrier devices.