Examination of internally delta-doped gallium arsenide resonant tunnelling structures

Studies of electron tunnelling through “internal double barriers” produced by n-type (silicon) and p-type (beryllium) delta (δ)-doping of GaAs are reported. Measurements of the current-voltage (I-V), dIdV and d2IdV2 characteristics at room temperature, 77 K and 4.2 K were made. The measurements show structure in the dIdV2 and d2IdV2 characteristics attributable to tunnelling into the 2D quantized levels formed in the well region. This is qualitative agreement with self-consistent calculations of the sub-band structure and I-V characteristics. The results indicate, however, the difficulty of obtaning sufficient control of the concentration and diffusion of the δ-doped layers to use this technique effectively to produce resonant tunnelling structures.