Research On The Effects Of Interface Trap On The InSb Photovoltaic Infrared Focal Plane Array

The imperfection of the InSb material(such as the existence of dangling bonds, impurities and defects near the surface) and the introduction of interface defects and impurities in the fabrication process by ICP etching, ion implantation or back-thinning form interface state, what mentioned above can increase the recombination rate near the interface and lead to the formation of interface traps. To the best of our knowledge, the effect of the interface traps on the performance of an infrared(IR) focal plane array(FPA) was seldom reported. To optimize an IR FPA, numerical simulation has become an important tool because it is cheaper and faster compared to the manufacturing of an IR FPA. In this paper, a simulation model for a photovoltaic InSb IR FPA is constructed, in which the electrical, optical and material properties of InSb, as well as the SRH, the Auger and the radiative recombination models, are considered. The main works have been done in this paper as follows:(1) By numerical simulations, the influence of interface states on the transient characteristics of a photovoltaic InSb IR FPA is studied. The generation rate, the hole concentration, the electric field, the hole current density and the recombination rate are analyzed to reveal the intrinsic mechanisms of the influence of the interface traps on the transient characteristics. The introduction of interface traps decreases the photoresponse of the photovoltaic InSb IR FPA. The influence of interface states densities on the transient characteristics of a photovoltaic InSb IR FPA is analyzed by the microscopic physical parameters, such as the current, the electric field, the generation rate and the recombination rate. The photoresponse of the photovoltaic In Sb IR FPA decreases sharply with the increase of the interface states density.(2) By numerical simulations, the influence of interface states on the steady-state performance(such as the crosstalk and the quantum efficiency) of a back-illuminated photovoltaic InSb IR FPA is studied. The distributions of the generation rate, the hole concentration, the electric field, the hole current density and the recombination rate are analyzed to reveal the intrinsic mechanisms of the influence of the interface traps on the crosstalk of the FPA. And the trends of the effect of the density and the position of the interface states on the crosstalk are summarized. The interface traps on the surface of the InSb absorber layer and the space between two pixel mesas decrease the crosstalk effectively. And the crosstalk decreases sharply with the increase in the interface trap density. The intrinsic mechanisms of the influence of interface states on the quantum efficiency of a back-illuminated photovoltaic InSb IR FPA are analyzed by the distributions of the microscopic physical parameters, such as the generation rate, the hole concentration, the hole current density, and the recombination rate. The photoresponse of the photovoltaic InSb IR FPA decreases sharply with the increase of the interface states density. And the trends of the effect of the density and the position of the interface states on the quantum efficiency are summarized. The introduction of the interface traps decreases the quantum efficiency, and the quantum efficiency decreases sharply with the increase in the interface trap density. It is the interface traps on the surface of the InSb absorber layer that decrease the quantum efficiency most. In a word, the existence of the interface states decreases the quantum efficiency, as well as the crosstalk, which indicates the fact that IR detector designers should treat the interface traps objectively according to the design demand.