CHARACTERISTICS OF GAAS GRADED-PERIOD DELTA-DOPED SUPERLATTICE

In the paper, the characteristics of a GaAs graded-period delta-doped superlattice grown by molecular beam epitaxy are studied. It is shown that a novel S-shaped negative differential conductivity (NDC) occurs both at 300 K and 77 K. An N-shaped NDC due to the temperature-induced tunnelling effect is observed at 300 K. In addition, a two-state avalanche multiplication process, i.e. a middle quasistable region, is seen at 77 K. Finally, there is an interesting hysteresis phenomenon owing to the trapped holes created by the avalanche multiplications.