1、 Material characteristics and usage restrictions

1. Temperature sensitivity
   • core issueThe bandgap width of HgCdTe varies significantly with temperature (about -2 meV/K), resulting in a drift of the cutoff wavelength and dark current with temperature.
   • Precautions：
     • Must work in a low-temperature environment (usually 77K or lower, liquid nitrogen refrigeration or Stirling refrigeration).
     • Temperature fluctuations should be controlled within ± 0.1K, otherwise it may cause wavelength shift or noise surge.
   • caseA certain long wave infrared detector has a dark current of 10 ⁻³ A/cm ² at 300K, which decreases to 10 ⁻⁹ A/cm ² at 77K, indicating excellent cooling effect.
2. Mechanical brittleness
   • core issueHgCdTe has a large lattice constant and is prone to dislocation and crack formation.
   • Precautions：
     • Avoid mechanical vibration and impact, and use shockproof packaging during transportation.
     • Flexible leads (such as gold wire ball bonding) are used during packaging to avoid breakage caused by thermal stress.

2、 Optical and Electrical Design

1. Optical window matching
   • core issueThe detector needs to match the wavelength range of the optical system, otherwise the sensitivity will decrease.
   • Precautions：
     • Select the coating window based on the cut-off wavelength of the detector (e.g. 3-5 μ m medium wave, 8-14 μ m long wave).
     • Avoid using high refractive index materials (such as certain glasses) in direct contact with the detector surface to prevent reflection loss.
2. Bias voltage control
   • core issueExcessive bias voltage can cause tunneling effect, leading to a surge in dark current.
   • Precautions：
     • The bias voltage should be strictly limited to the manufacturer's recommended range (such as -0.1V to -0.5V).
     • Use a low-noise power supply to avoid voltage fluctuations introducing noise.

3、 Environment and storage conditions

1. Vacuum and Cleanliness
   • core issueThe surface of HgCdTe is prone to oxidation, leading to performance degradation.
   • Precautions：
     • Storage and operation should be carried out in a vacuum or inert gas (such as nitrogen) environment.
     • The vacuum degree after packaging should be better than 10 ⁻⁶ Torr to prevent water vapor and oxygen from entering.
2. radiation protection
   • core issueHigh energy radiation (such as gamma rays) can cause lattice damage, leading to an increase in dark current.
   • Precautions：
     • Avoid use in strong radiation environments and add a lead shielding layer if necessary.
     • Long term storage should be kept away from radioactive substances.

4、 Operation and maintenance standards

1. Preheating and Cooling
   • core issueRapid temperature changes may cause thermal stress damage.
   • Precautions：
     • Before starting up, it is necessary to slowly cool down (such as taking ≥ 30 minutes from room temperature to 77K).
     • After shutting down, maintain low temperature for at least 1 hour and wait for the internal temperature to reach equilibrium before heating up again.
2. Electrostatic protection
   • core issueHgCdTe is sensitive to static electricity, and ESD may cause damage.
   • Precautions：
     • Operators need to wear anti-static wristbands and the workbench should be grounded.
     • The detector should be stored in an anti-static bag to avoid direct contact with plastic or synthetic materials.

5、 Common faults and troubleshooting

1. Abnormal dark current
   • Possible reasonsHigh temperature, excessive bias voltage, and surface contamination.
   • Troubleshooting steps：
     1. Check the refrigeration system and confirm that the temperature is stable.
     2. Reduce the bias voltage to the recommended value and observe the changes in dark current.
     3. If the abnormality persists, it is necessary to return to the factory for cleaning or recoating.
2. Decreased response rate
   • Possible reasonsOptical window contamination and detector degradation.
   • Troubleshooting steps：
     1. Check the transparency of the window and clean or replace it if necessary.
     2. Test the response rate at different temperatures to confirm if it is material degradation.