Carrier Flow
An intrinsic component of diode behavior in semiconductor devices originates from the thermal generation of minority carriers near the depletion region. This electronic phenomenon is called diffusion leakage current and represents the fundamental limit of sensor isolation in silicon junctions. The current arises when minority carriers diffuse to the edge of the depletion region and are swept across by the electric field.
It establishes the baseline noise floor in uncooled photodiodes, making it a parameter of interest in low-level signal detection.
Thermal Behavior
Exponential growth characterizes this current as temperatures rise because of the relationship between intrinsic carrier concentration and thermal energy. High temperatures accelerate the leakage, which doubles approximately every eight degrees Celsius in silicon. This thermal sensitivity dominates sensor drift in high-temperature applications.
Metrological Impact
Measurement uncertainty in low-level current characterization increases when the leakage dominates the sensor output. High-precision electrometers must resolve the diffusion leakage current from other noise sources during wafer-level testing.
Mitigation Strategy
Doping profile optimization reduces this unwanted carrier flow by limiting the lifetime of minority carriers in the active region. Applying this technique allows the diffusion leakage current to remain below specified thresholds even at elevated operating temperatures. Silicon-on-insulator technology represents another physical boundary that limits this drift.
