Vacuum Annealing and Passivation of HfS2 FET for Mitigation of Atmospheric Degradation

Vikrant UPADHYAYA  Toru KANAZAWA  Yasuyuki MIYAMOTO  

Publication
IEICE TRANSACTIONS on Electronics   Vol.E100-C   No.5   pp.453-457
Publication Date: 2017/05/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.E100.C.453
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
Category: 
Keyword: 
HfS2,  field effect transistors,  environmental degradation,  passivation,  PMMA,  vacuum annealing,  

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Summary: 
The performance of devices based on two dimensional (2D) materials is significantly affected upon prolonged exposure to atmosphere. We analyzed time based environmental degradation of electrical properties of HfS2 field effect transistors. Atmospheric entities like oxygen and moisture adversely affect the device surface and reduction in drain current is observed over period of 48 hours. Two corrective measures, namely, PMMA passivation and vacuum annealing, have been studied to address the diminution of current by contaminants. PMMA passivation prevents the device from environment and reduces the effect of Coulomb scattering. Improvement in current characteristics signifies the importance of dielectric passivation for 2D materials. On the other hand, vacuum annealing is useful in removing contaminants from the affected surface. In order to figure out optimum process conditions, properties have been studied at various annealing temperatures. The improvement in drain current level was observed upon vacuum annealing within optimum range of annealing temperature.