The Study Of Mid-wavelength And Long-wavelength HgCdTe Focal Plane Infrared Detector Based On Artificial Photonic Microstructure Modulation

In this paper, numerical simulation and theoretical analysis have been done on new types of mid&long-wavelength focal plane Hg Cd Te infrared detector based artificial photonic microstructures. By revealing the impact of artificial microstructure design on the performance of device, it is of great significance for light field control to enhance the performance of Hg Cd Te infrared detector. Reliable criterions have been provided to improve or optimize the fabrication process of Hg Cd Te infrared detector, and Basic guidance have been released for the engineering applications of Hg Cd Te infrared. By introducing artificial photonic microstructures, the noise that caused by the dark current can be significantly reduced, while maintaining the same detection rate as ordinary ones, and thereby the performance of device is improving. The research results can offer theoretical and technical support for improving the performance of the third generation to Hg Cd Te focal plane infrared detector.First, there is a success in calculating at the time in the field of two-dimensional and three-dimensional simulation by coupling finite difference time domain method(FDTD) light field into the finite element(FEM) numerical simulation of semiconductor devices. FDTD and FEM simulation are associated after combining metal dispersion model, conductivity absorption model, drift diffusion model, the Poisson equation, current continuity equation, etc. Two-dimension "optical" and "electricity" simulation for different sizes of pillars of the structure in devices, and three-dimension "optical" and "electricity" simulation for different sizes of metal gate- Media- metal structure in devices are carried on to calculate the light absorption spectrum, the light response spectrum, dark current and the electric field distribution. By analyzing the changes of dark current and quantum efficiency, the design scheme can be acquired for decreasing the dark current while maintaining high quantum efficiency.Secondly, the subwavelength light trapping structure photovoltaic Hg Cd Te infrared detector, and the surface plasmon enhanced photoconductive Hg Cd Te infrared detector are designed. The key optical and electrical design parameter database of Hg Cd Te infrared detectors is established, such as mobility, minority carrier lifetime, diffusion length, the band gap, dielectric constant, conductivity, absorption coefficient, and etc. And the dispersion model, the drift diffusion model and the conductivity model are improved. Several typical device structure, such as pillars, holes or metal gate- media – metals are constructed. For periodic pillar structure of photovoltaic devices, it is found that a strong light trapping effect for low filling factor in this pillar structure, and the goal can be achieved to reduce the dark current by reducing the volume while the response rate stay unchanged. Compared to conventional mesa or planar n-on-p / p-on-n structure, the light trapping effect in pillar structure not only improves the performance of the device but also is compatible with large scale focal plane array, which showing a good practical prospect. For the metal gate- dielectric- metal photoconductive device, the metal surface plasmon for local modulation of the light field, can enhanced the intensity of the light field and increase the interaction time of the light and the medium, thereby increasing the detector sensitivity and response rate.Finally, referring to the theoretical obtained size parameters of the devices, preliminary experimental study is carried on by electron beam lithography method for ultra-thin photoconductive Hg Cd Te detector whose optical absorption is enhanced by surface subwavelength metallic grating structure.