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Anomalous Conductivity Switch Observed in Treated Hafnium Diselenide Transistors
Author(s) -
Albagami Malak,
Alrasheed Abdullah,
Alharbi Mervat,
Alhazmi Abrar,
Wong Kin,
Qasem Hussam,
Alodan Sarah,
Alolaiyan Olaiyan,
Wang Kang L.,
Amer Moh. R.
Publication year - 2020
Publication title -
advanced electronic materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.25
H-Index - 56
ISSN - 2199-160X
DOI - 10.1002/aelm.201901246
Subject(s) - materials science , hafnium , raman spectroscopy , optoelectronics , conductivity , schottky barrier , band gap , fermi level , semiconductor , diselenide , doping , optics , diode , chemistry , zirconium , selenium , metallurgy , physics , quantum mechanics , electron
Layered hafnium diselenide (HfSe 2 ) is an emerging Van der Waals semiconductor in which a hafnium layer is sandwiched between two selenium layers. Owning to its indirect band gap with magnitudes close to silicon's band gap and high predicted carrier mobility, hafnium diselenide material is a strong candidate for device applications. Here, the effect of laser treatment on 2H‐ HfSe 2 devices is shown in ambient conditions using µ‐Raman spectroscopy. It is shown that an emerging Raman peak evolves with increasing laser exposure time. It is also shown that top‐down fabricated 2H‐HfSe 2 devices exhibit an anomalous p‐type behavior post laser treatment, with I on / I off ratio as high as 10 3 . This anomalous conductivity change can be observed after thermal and electrical annealing. For bottom‐up devices, it is observed that p‐type conductivity with remarkable I on / I off ratio reaching 10 4 . This conductivity switch can also be shown on 1T‐HfSe 2 devices post laser irradiation and high V ds bias treatments. Based on the circuit model, this conductivity switch is attributed to contact doping caused by an increase in the Schottky barrier height at each contact, which shifts the Fermi energy closer to the valance band. These results demonstrate a unique conductivity switching mechanism for HfSe 2 ‐FET devices.