  In the pursuit of room temperature quantum hardware, our study introduces a
gate voltage tunable quantum wire within a tri-gated n-type junctionless
MOSFET. The application of gate voltage alters the parabolic potential well of
the tri-gated junctionless MOSFET, enabling modification of the nanowire's
potential well profile. In the presence of light, photogenerated electrons
accumulate at the center of the junctionless nanowire, aligning with the
modified potential well profile influenced by gate bias. These carriers at the
center are far from interfaces and experience less interfacial noise.
Therefore, such clean photo-doping shows clear, repeatable peaks in current for
specific gate biases compared to the dark condition, considering different
operating drain-to-source voltages at room temperature. We propose that
photodoping-induced subband occupation of gate tunable potential well of the
nanowire is the underlying phenomenon responsible for this kind of observation.
This study reveals experimental findings demonstrating gate-induced switching
from semi-classical to the quantum domain, followed by the optical occupancy of
electronic sub-bands at room temperature. We developed a compact model based on
the Nonequilibrium Green's function formalism to understand this phenomenon in
our illuminated device better. This work reveals the survival of the quantum
confinement effect at room temperature in such semi-classical transport.
