Specific features of quasineutral carrier transport modes in semiconductors and semiconductor structures

摘要

It has been demonstrated that the field dependence of the electron and hole mobility strongly affects the carrier distribution in semiconductor structures under quasineutral conditions. Taking into account this phenomenon, a new equation for quasineutral carrier transport in semiconductors and semiconductor structures has been suggested. The concept of the critical current density j_(cr) has been introduced and validated. At j j_(cr), the suggested equation transforms to the well-known 'classical' equation of quasineutral transport. By contrast, at j > j_(cr), novel solutions become apparent from the suggested equation. The performed analysis gives insight into what happens in regions in which the quasineutral drift and DSQD (diffusion stimulated by quasineutral drift) modes predominate. Analytical expressions have been derived for the dependences of the voltage drops across the quasineutral drift and DQSD regions on current. It has been shown that, at high current densities, the voltage drop across the DSQD region tends to decrease as the current density increases. The results obtained enable a qualitative interpretation of the negative differential conductivity region in the current-voltage characteristic of forward-biased semiconductor structures, which arises at high current densities.