Mechanism of dark current dependence on reverse voltage in mid-wavelength infrared HgCdTe mesa PIN avalanche diode

Abstract

Mid-wavelength infrared HgCdTe avalanche photodiodes (APDs) are becoming increasingly significant in research and practical applications for the high linear gain, low excess noise and high quantum efficiency. However, the performance of HgCdTe APDs is largely limited by the voltage dependence of dark current. It has been well known that the tunneling current is the main component of the dark current of the p-i-n diode. However, the current contribution of different physical mechanism still needs to be indicated in different reverse voltages. In this paper, we mainly study the mechanism of the relationship between dark current and reverse voltage of mid-wavelength infrared $${\text{Hg}}_{1 - x} {\text{Cd}}_{x} {\text{Te}}$$ (x = 0.3) mesa p-i-n avalanche diode. Several physical models are used for the dark current numerical simulation. The results show that for detection of $${\text{Hg}}_{1 - x} {\text{Cd}}_{x} {\text{Te}}$$ mesa p-i-n detector under low temperature, dark current is mainly caused by tunneling current. With the reverse voltage increasing, the main component of dark current turns from trap-assisted tunneling current to direct band-to-band tunneling. The transition voltage is positively related to the energy level difference between trap energy level and conduction band. The results may provide a guideline to improve the performance of the mid-wavelength infrared APD detector by ranking the importance of different structural parameters.