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A High‐Photocurrent and Fast‐Response Polarity‐Controlled ZnO‐Based UV Photodetector Grown by a Sol–Gel Process
Author(s) -
Lee GunWoo,
Baek SeungHye,
Kim HeeWung,
Lee SungNam
Publication year - 2021
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.202000501
Subject(s) - materials science , sapphire , photocurrent , photoluminescence , layer (electronics) , polarity (international relations) , polar , optoelectronics , photodetector , thin film , nanotechnology , optics , chemistry , laser , biochemistry , physics , astronomy , cell
Oxygen‐polar (O‐polar) and nonpolar ZnO‐based UV photodetectors (PDs) are fabricated using a sol–gel (SG) method on polarity‐controlled ZnO seed layers grown by atomic layer deposition (ALD). O‐polar c ‐plane and nonpolar a ‐plane ZnO films grown using the SG process are obtained using ALD‐grown ZnO seed layers on c ‐plane and r ‐plane sapphire substrates, respectively. In addition, the photoluminescence intensity of the O‐polar c ‐plane ZnO film is higher than that of the nonpolar a ‐plane ZnO film owing to the introduction of the ZnO seed layer. Therefore, the resulting photocurrent of the O‐polar c ‐plane ZnO PD is higher than that of the nonpolar a ‐plane ZnO PD. Furthermore, regardless of the crystal polarity, the carrier concentration and the mobility of the ZnO film deposited using the SG method significantly increase because of the ZnO seed layer. In particular, the carrier concentration of the nonpolar a ‐plane ZnO film is 2.5 times higher than that of the O‐polar c ‐plane ZnO film. Therefore, the time‐dependent photoresponsivity of the nonpolar a ‐plane ZnO PD is faster than that of the O‐polar c ‐plane ZnO PD. These results indicate that the ZnO seed layers can effectively control the crystal polarity of ZnO films grown using the SG method.