The performance of InP/InGaAs SPAD detectors depends on the electrical field distribution in their multiple layers. In the conventional separate absorption, grading, charge and multiplication (SAGCM) structure, the major function of the charge layer is to confine the electrical fields, so the charge layer’s parameter design is very important for any enhanced SPAD detectors. Normally the sheet density equals to doping concentration times thickness is considered as one of the key factors for the device design, however, even with the same sheet density, there are different combinations of doping densities and thicknesses. Our calculations show that with the same sheet density of charge layer, the one with higher doping concentration has higher electrical fields in both multiplication and absorption layers, then has lower breakdown and punch-through voltages. The results were also verified by the experimental measurements.
The type-II InAs/GaSb superlattices have been recognized as popular materials for the third-generation infrared focal plane detectors. In recent years, the performances of the type ii superlattice infrared focal plane have been improved dramatically. High operating temperature can be achieved by using the monopolar barrier structure of InAs/GaSb type ii superlattice material system. In this paper, the nBn type (also known as Bariodes) mid-wavelength infrared detector based on InAs/GaSb type ii superlattice is studied. As the device has no depletion layer, the recombination and trap assisted tunneling effects are inhibited, and the dark currents are effectively reduced. Based on the equivalent material method, the relationship between the dark current and the doping concentration, thickness and composition of the barrier layer and absorption layer was analyzed in detail, and the optimal working condition was pointed out.
The nBn barrier medium-wave infrared detector is widely used in the field of night defense vision with internal gain. Due to its low dark current and high reliability. As the existence of its barrier layer suppresses the majority carrier current with a low electric field, the electric field distribution inside the device is one of the important factors affecting its performance. In particular, the electric field distributions of the barrier layer show directly effects on the overall performance of the detector. In this paper, Apsys software is used to simulate the absorption layer and the nBn InAs1-xSbx/AlAs1-ySby mid-wave infrared detector with the factors of thickness, composition and doping changes. and the influence of the above factors on the electric field of the device is also analyzed.