EXAMINATION OF INTERNALLY DELTA-DOPED GALLIUM-ARSENIDE RESONANT-TUNNELING STRUCTURES

Studies of electron tunnelling through ''internal double barriers'' pr oduced by n-type (silicon) and p-type (beryllium) delta (delta)-doping of GaAs are reported. Measurements of the current-voltage (I-V), dI/d V and d(2)I/dV(2) characteristics at room temperature, 77 K and 4.2 K were made. The measurements show structure in the dI/dV and d(2)I/dV(2 ) characteristics attributable to tunnelling into the 2D quantized lev els formed in the well region. This is in qualitative agreement with s elf-consistent calculations of the sub-band structure and I-V characte ristics. The results indicate, however, the difficulty of obtaining su fficient control of the concentration and diffusion of the delta-doped layers to use this technique effectively to produce resonant tunnelli ng structures.