The Study Of MSM Ultraviolet Photodetector Based On MgZnO

In recent years, MgZnO solar-blind photodetectors (SBPDs) have drawn a greatdeal of interest because of their wide applications in ultraviolet communications,missile warning and flame monitoring. According to the classical semiconductortheory and the experiment, a two-dimensional physical model of the MgZnO metal-semiconductor-metal (MSM) photodetector is developed. The influences of thedifferent electrode structures for the detector’s characteristics are obtained based on themodel. The main studies and conclusive results are as follows:First, considering the basic material properties of MgZnO, a two-dimensionalnumerical physical model based on the coupled Poisson’s equation and time-dependentcontinuity equations is established. Numerical simulation and experimental data ofsymmetric MSM detector were compared to demonstrate the accuracy of the model.The longitudinal and transversal distribution of the electric field and the currentcharacteristics of the detector are calculated. Moreover, the performance of the detectorwith different electrode widths and spacing are also investigated.Second, based on the theory of geometrical optics, the new optical generation ratemodel of MgZnO MSM photodetector considering the contribution from thesemicircular or triangular electrode reflection is achieved. The steady-statecharacteristics and transient response are discussed. Compared with the conventionalelectrode, semicircular and triangular electrode devices exhibit a substantialimprovement on the photocurrent. This is due to the fact that under the sameillumination the novel electrode structures will redirect some fraction of the incidentultraviolet beams to photosensitive area to increase the photocurrent.Last, the application of asymmetric Schottky barrier and electrode area in MgZnOMSM photodetector has been investigated, which demonstrates that the asymmetricstructures can effectively suppress dark current and without the reduction of thephotocurrent. Then, the effects of asymmetric Schottky barrier of semicircular ortriangular electrode MgZnO MSM detector are also discussed.