Structures include a tunneling device disposed over first and second lattice-mismatched semiconductor materials. Process embodiments include forming tunneling devices over lattice-mismatched materials.

A semiconductor device includes a first diode connected transistor of a first conductivity type and a second diode connected transistor of a second conductivity type connected in series, each of the first and second diode connected transistors being configured to exhibit negative differential resistance in response to an applied voltage. The first drain and first source regions of the first diode connected transistor include dopants of the first conductivity type at degenerate dopant concentration levels and a gate of the first diode connected transistor has a work function that corresponds to that of the semiconductor containing dopants of the second conductivity type. The second drain and second source regions of the second diode connected transistor include dopants of the second conductivity type at degenerate dopant concentration levels and a gate of the second diode connected transistor has a work function that corresponds to that of the semiconductor containing dopants of the first conductivity type.