MBE grown tri-layer 2H-MoTe2 quantum wells coupled with WSe2 carrier reservoir for resonant tunneling device applications

In this work, we report the wafer scale growth of high-quality, ultra-thin (3L) MoTe2 quantum wells using molecular beam epitaxy on a HfO2/WSe2 heterostructure. The structural and morphological quality of the 2H-MoTe2 was confirmed via in situ reflection high energy electron diffraction pattern and its oscillations, XPS, and AFM spectroscopy. The underlying WSe2, grown by chemical vapor deposition, retains its crystallinity and integrity throughout the growth process, as verified by HR-TEM, XRD, and XPS measurements. Cryogenic transport measurements reveal a distinct resonant tunneling peak in the vertical device structure comprising n-WSe2/HfO2/MoTe2/HfO2/Au. Complementary quantum transport modeling based on the non-equilibrium Green’s function formalism further elucidates the role of quantum well width above the excitonic Bohr radius (∼0.7 nm) in tuning the resonant tunneling behavior along with fundamental insights due to phonon-induced decoherence, a key limiting factor in 2D-quantum materials and devices. Therefore, the present work may provide the route for the fabrication of 2D-MoTe2-based quantum devices with further development in high frequency devices, terahertz-emitters, and future quantum processing operations at ultra-low temperatures.