Impact ionization in InAlAs/InGaAs/InAlAs HEMT's

The kink effect and excess gate current in GaAs/InGaAs/InAlAs HEMs have bee n linked to impact ionization in the high field region of the channel. In t his letter, a relationship is established between experimentally measured e xcess gate current and the tunneling of holes from the quantum well formed in the channel. The channel hole current is then obtained as the quotient o f the excess gate current to the gate-voltage-dependent transmission probab ility This channel hole current follows the exponential dependence of the i onization constant on the inverse electric held.