Photoconduction properties and anomalous power-dependent quantum efficiency in non-polar ZnO epitaxial films grown by chemical vapor deposition
Journal
Applied Physics Letters
Journal Volume
110
Journal Issue
5
Pages
052101-1- 052101-5
Date Issued
2017
Author(s)
Abstract
Photoconduction (PC) properties in the ZnO films with the (110) nonpolar surface (a-plane) epitaxially grown by chemical vapor deposition on the LiGaO2 (010) substrates with low lattice mismatches (4.0% along the c-axis and 3.8% along the m-axis) have been studied. The structural and optical qualities of the epitaxial films have been characterized using theta-two theta and phi scans, X-ray diffraction, rocking curve, and photoluminescence measurements. The nonpolar ZnO film exhibits a near visible-blind ultraviolet photoresponse. The optimal photocurrent to dark current ratio (i.e., sensitivity) can reach 13360%. The responsivity of the a-plane ZnO photoconductor-type detector can also reach 17 AW−1, which is two to four orders of magnitude higher than those of the m-plane, a-plane, and r-plane photodiodes based on ZnO/ZnMgO quantum wells. The normalized gain at 2.9 cm2V−1 of the nonpolar film is also comparable with the optimal recorded value of the ZnO nanowires. In addition, the PC mechanism has also been investigated by the power-dependent and time-resolved photoconductivity measurements. The power-sensitive responsivity can be attributed to the effect of light intensity on carrier lifetime and quantum efficiency. The photovoltaic effect of the surface depletion region is inferred to be the reason resulting in the anomalous power-dependent quantum efficiency. © 2017 Author(s).
SDGs
Other Subjects
Carrier lifetime; Chemical vapor deposition; Deposition; Efficiency; Epitaxial films; Epitaxial growth; Lattice mismatch; Metallic films; Photoconducting materials; Photovoltaic effects; Semiconductor quantum wells; Vapor deposition; X ray diffraction; Zinc oxide; Dark current ratio; Epitaxially grown; Non-polar surfaces; Normalized gains; Optical qualities; Orders of magnitude; Photoluminescence measurements; Surface depletion; Quantum efficiency
Publisher
American Institute of Physics Inc.
Type
journal article