Negative differential infrared photoconductivity in quantum-dot structures

Using a simple model for monopolar quantum-dot structures which takes into account the heating of mobile (unbound) electrons, we calculated the current–voltage characteristics of these structures under infrared illumination and revealed the origin of the effect of negative differential infrared photoconductivity observed in recent experiments. It is clarified also why decreasing photocurrent–voltage characteristics coexist with steep rising dark current–voltage characteristics.