Band-modulation of MgZnO/ZnO Metal-semiconductor-metal Photodetectors

Department of Electrophysics, National Chiayi University, Chiayi, Taiwan, China.

^* Corresponding author: jundar@mail.ncyu.edu.tw

Abstract

Magnesium (Mg) diffusion behavior on the band modulation of MgxZn1-xO/ZnO metal-semiconductor-metal photodetectors (MSM-PDs) was studied. As the annealing temperature increases, Mg atoms diffuse from MgxZn1-xO into the underlying ZnO layer, which modulates the detection band of the fabricated MSM-PDs from two distinct bands into one band. For the annealing temperature lower than 900 ºC, two detection bands were achieved located in the wavelength region of 280–320 nm and 360–400 nm, attributed to the absorption of the MgxZn1-xO and the ZnO layer, respectively. When the annealing temperature is raised to 900 ºC, the MgxZn1-xO/ZnO bi- layer becomes homogenized into a single MgxZn1-xO layer, leading to only one detection band with a wavelength region of 280–340 nm. In the photoluminescence measurement, the as-deposited MgxZn1-xO/ZnO bi-layer demonstrates two distinct emission peaks located at about 340 and 400 nm for the absorption of the MgxZn1-xO and ZnO layers, whereas only one emission peak of 355 nm was observed in the 900 ºC-annealed MgxZn1-xO/ZnO bi-layer.