Charge Imbalance

To utilize the benefit of SJ structures to the maximum, the principle of charge compensation must be satisfied as

And, the doping integral over a layer perpendicular to the current flow direction remains smaller than the specific breakthrough charge for silicon of about 2 x 1012cm-2 (Deboy et al., 1998). Thus, the enhanced doping level of the current carrying n region results in a significant drop in resistivity.

Experimental data from Shenoy et al. (1999) reveal that the change of Vbr in a SJ structure is dependent on the value of the charge imbalance (i.e. AQ = |Qp — Qn|). It becomes lower when AQ increases. Other effects on charge imbalance to the device transient performance include higher electric field, peak recovery current, and higher turn-off losses. Numerical simulations prove

Electric field plots along (a) x = 5 цm and (b) x = 2.5 at different Fdsthat the SJ device is highly sensitive to charge imbalance especially for devices designed for low on-state resistance

Fig. 6.7. Electric field plots along (a) x = 5 цm and (b) x = 2.5 at different Fdsthat the SJ device is highly sensitive to charge imbalance especially for devices designed for low on-state resistance.

 
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