In this paper, we focus on the influence of thermal treatment on the passivation of silicon nitride (SiN<sub>x</sub>) film of p-i-n InGaAs detector. In our experiment, the perimeter/area (P/A) test diodes are fabricated by using two different device processes, and the relationship between the dark current density and P/A is investigated. The results indicate that the thermal treatment in the vacuum can be able to improve the passivation SiN<sub>x</sub> film effect and thus suppress the perimeterrelated current with the decrease of two orders of magnitude. Then the analysis of dark current source is carried out. The result shows that the sample with SiN<sub>x</sub> film through thermal treatment is composed of diffusion current and ohmic current, on the contrary, the other mainly consists of surface leakage current and diffusion current. It is illustrated that the passivation effect of SiN<sub>x</sub> was strengthened after thermal treatment and surface leakage current can be suppressed.
The single-pixel extended wavelength mesa InGaAs/InAsP SWIR detector was reported. The properties of the detector were characterized and analyzed at 160K~300K. At the operating temperature of 200K , the dark current density is 1.37×10<sup>4</sup> nA/cm<sup>2</sup>(@-10mV), the cut-off wavelength is 2.43μm, the peak detectivity and the peak responsivity are 3.44×10<sup>11</sup>cmHz<sup>1/2</sup>W<sup>-1</sup> and 1.41A/W, respectively. Through analysis of the dark current source, the analysis of reverse dark current indicates that the tunneling current plays an important role at high voltage or relatively low temperature, and at near room temperature and low bias voltage, the generation-recombination current is the main current source instead of ohmic current based on thermal activation energy approximate to E<sub>g</sub>/2 and the bias-voltage characteristic of the first order derivative of dark current, while the zero-voltage current mainly consists of the interface current and the thermal background current.