Preparation and Ultraviolet Detection Performance Study of Porous n-GaN/p-ZnxCu1_xS Heterojunctions
In this paper,porous n-GaN thin films with a pore density of 1.51 × 1010 cm-2 and an average pore size of 38 nm were initially prepared by UV-assisted electrochemical etching(UV-EC).Subsequently,a series of ZnxCu1-xS composite films,with x values of 0.0,0.2,0.4,0.6,0.8 and 1.0,were deposited on the porous n-GaN films by water bath method.The bandgaps of the porous n-GaN/ZnxCu1-xS heterojunctions varied in the range from 2.34 eV to 3.51 eV.Hall test results demonstrate that when x values is less than 1,the Znx Cu1-xS composite films exhibit p-type semiconductor properties.Furthermore,increasing the proportion of CuS leads to an improvement in the conductivity of the composite films.Additionally,XPS results confirm that both Cu and Zn possess a+2 valence within the composite films.When ZnxCu1-xS forms a heterojunction with porous n-GaN,the energy band structures of both materials interact to create a built-in electric field.This field facilitates the efficient separation of photogenerated electron-hole pairs.Finally,p-n heterojunctions UV detectors were constructed based on these heterostructures.The I-V curve results indicate that these detectors exhibit good rectification characteristics.Notably,the n-GaN/p-Zn0.4Cu0.6S detector demonstrates optimal performance.In the dark state,I+3V/I-3V is approximately 1.78 × 105.Under a bias voltage of-3 V and an optical power density of 432 μW/cm2(ultraviolet light at 365 nm),this detector's photo-to-dark current ratio exceeds 103,the rise/fall time is 0.09/39.8 ms,responsivity®reaches 0.352 A/W,the external quantum efficiency(EQE)stands at 119.6％,and detectivity(D*)is 3.21 × 1012 Jones.The I-t curve results indicate that the porous n-GaN/p-ZnxCu1-xS heterojunctions UV detector possesses reproducible performance during the consecutive on-off optical cycling process with reproducible photocurrent response.This study offers valuable theoretical insights and a comprehensive understanding of the physical properties and performance characteristics of these novel heterostructures UV detectors.
p-ZnxCu1-xSporous n-GaNheterojunctionultraviolet detectorphoto-to-dark current ratioresponsivity
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