Role of ZrO₂ Passivation Layer Thickness in the Fabrication of High‐Responsivity GaN Ultraviolet Photodetectors

Abstract

The importance of a ZrO2 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 ZrO2 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 ZrO2 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.

Comprehensively Improved Performance of β-Ga2O3 Solar-Blind Photodetector Enabled by a Homojunction with Unique Passivation Mechanisms

“…In fact, the surface passivation by inserting/capping a foreign layer was demonstrated to be an effective technique for suppressing bulk/surface leakage current and reducing I dark in MSM PDs based on other semiconductors, e.g., Ge, 20 GaAs, 21 and GaN. 22 However, to the best of our knowledge, there is no report investigating the effects of surface passivation on Ga 2 O 3based PD so far except reference, 23 in which β-Ga 2 O 3 MSM PD was passivated with 20 nm Al 2 O 3 film for suppressing persistent photoconductivity (PPC). Unfortunately, in that work, I photo was also reduced after passivation because of the introduction of a blocking layer, which is detrimental to photodetection sensitivity.…”

Ultranarrow Band UV Detection in GaN with Simple Device Architecture

“…The measurement procedure of rise time ( τ r ) and decay time ( τ d ) is reported elsewhere. [ 23,35 ] The values of τ r and τ d are found to be limited by the hole trapping at defect states, which is a well‐known phenomenon in GaN. [ 4,36 ]…”

Lattice-aligned gallium oxynitride nanolayer for GaN surface enhancement and function extension

“…The proposed GaON nanolayer can improve the device performance by suppressing the dark background current and thus enhancing the responsivity (sensitivity). Although GaN-based UV photodetector stimulates a lot of interest owing to its suitable detection range in UV, versatility and ability to serve in an extreme environment, a common challenge remains as the small photo-to-dark current ratio of less than 10 3 [49,50]. Therefore, an oxide layer, such as ZnO and ZrO 2 , is usually used to suppress the dark current that is mainly carried by holes in VB [51,52].…”