EFFECT OF NONPARABOLICITY ON THE LIFETIME LIMITED ULTIMATE FREQUENCY IN RESONANT-TUNNELING DIODES

Using a two-band model accounting for the nonparabolicity of bulk band structure, the ultimate frequency limited by the lifetime of the lowe st quasibound state in double-barrier resonant tunneling structures is calculated. Better agreement with the experiment is achieved compared with the commonly adopted one-band model. It is shown that there are two competing effects resulted from the nonparabolicity, which would l ead to a longer or shorter lifetime depending on the structure and mat erial parameters.