As transistor footprint scales down to sub-10 nm regime, the process
development for advancing to further technology nodes has encountered
slowdowns. Achieving greater functionality within a single chip requires
concurrent development at the device, circuit, and system levels.
Reconfigurable transistors possess the capability to transform into both n-type
and p-type transistors dynamically during operation. This transistor-level
reconfigurability enables field-programmable logic circuits with fewer
components compared to conventional circuits. However, the reconfigurability
requires additional polarity control gates in the transistor and potentially
impairs the gain from a smaller footprint. In this paper, vertical transistors
with ambipolar MoTe2 channels are fabricated using the transfer-metal method.
The efficient asymmetric electrostatic gating in source and drain contacts
gives rise to different Schottky barriers at the two contacts. Consequently,
the ambipolar conduction is reduced to unipolar conduction due to different
Schottky barrier widths for electrons and holes. The current flow direction
determines the preferred carrier type. Temperature-dependent measurements
reveal the Schottky barrier-controlled conduction in the vertical transistors
and confirm different Schottky barrier widths with and without electrostatic
gating. Without the complexity overhead from polarity control gates,
control-free vertical reconfigurable transistors promise higher logic density
and lower cost in future integrated circuits