Peculiarities of Reverse Current–Voltage Characteristics of GaAs Lo‐Hi‐Lo Impatt Diodes

In the current‐voltage (I–V) characteristics of Schottky‐barrier GaAs diodes having a complex doping profile in the base regions of n‐n⁺‐n type a strong current‐voltage dependence is observed in the prebreakdown region. Breaks are found to appear in these regions when with increasing V a sharp decrease of the differential conductivity dI/dV at a certain V = V_c, occurs. The tunnel currents in such structures are calculated. It is shown that the sharpest dI/dV decrease is caused by the spiking of the highly doped n⁺‐region, while the transition from the thermofield tunneling (maximum contribution to tunnelling current caused by carriers with an energy above the Fermi level in the metal) to the field tunneling (current maximum caused by carriers with an energy at the Fermi level) yields a less sharp change in dI/dV. The higher the concentration in the n⁺‐region, the greater are the tunnel currents. The greater the doping differences in the n⁺‐ and n‐regions the more distinct are the breaks. The dependences of V_c, and the I–V characteristics on doping strength and thickness of each of the regions of the n‐n⁺‐n diode are determined.