Premium
Role of ZrO 2 Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors
Author(s) -
Chatterjee Abhishek,
Khamari Shailesh K.,
Porwal Sanjay,
Sharma Tarun Kumar
Publication year - 2019
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201900265
Subject(s) - responsivity , passivation , materials science , optoelectronics , photodetector , ultraviolet , fabrication , layer (electronics) , oxide , epitaxy , nanotechnology , metallurgy , medicine , alternative medicine , pathology
The importance of a ZrO 2 passivation layer in the fabrication of high‐responsivity GaN‐based ultraviolet (UV) photodetectors (PDs) is discussed. It is found that an optimum thickness of the ZrO 2 layer exists, which plays a critical role in controlling the photoresponse and transient response of the device. Beyond the optimal thickness, the performance of PDs deteriorates, which is limited by the restricted tunneling of photogenerated carriers across the oxide layer. At an optimum ZrO 2 thickness of 3 nm, a spectral responsivity of 27 A W −1 at 361 nm is achieved at 4 V applied bias along with the fast response of the device with a rise (fall) time of 28 ms (178 ms), respectively. Such characteristics are found to be similar or better than the recently reported state‐of‐the‐art values for visible blind metal–semiconductor–metal PDs fabricated on GaN. The results confirm that the surface passivation with an optimal thickness of an oxide layer can be used to develop high‐responsivity GaN‐based UV PDs irrespective of having a large dark current, which is often inevitable due to the presence of a large density of dislocations in GaN epitaxial layers grown on foreign substrates.