Dark current suppression of very long-wavelength p-on-n HgCdTe infrared detectors via optimizing absorber layer carrier concentration

• The influences of absorber layer carrier concentration on dark current of VLW HgCdTe infrared detectors are investigated. • The dark current mechanisms of VLW HgCdTe device were analyzed in the temperature range of 40 K to 100 K. • The effects of different recombination mechanisms on minority carrier lifetime and dark current are discussed. • Carrier concentration of absorber layer below 1×10 15 cm -3 is suggested for VLW HgCdTe device. • SRH lifetime is an important factor limiting dark current of VLW HgCdTe detector. In this study, the very long-wavelength (VLW) p-on-n HgCdTe devices with different absorber layer carrier concentration are fabricated and their dark current density versus voltage (J-V) characteristics are analyzed. The results show that suppression tunneling current is of great significance for VLW device, and reducing absorber layer carrier concentration is an feasible method. The influences of carrier concentration on dark current density are discussed further, considering the dependence of minority carrier lifetime on carrier concentration. It is found that the tunneling current and generation-recombination current are the dominant dark current mechanism respectively when the absorber layer carrier concentration is above and below 1.0 × 10 15 cm −3 . The experiment and simulation results indicate that the n-type absorber layer with carrier concentration below 1.0 × 10 15 cm −3 and high Shockley-Read-Hall (SRH) lifetime is beneficial for the preparation of low dark current VLW p-on-n HgCdTe devices.