Study of the breakdown voltage in lateral polysilicon N+P junctions

Lateral N+P junctions are realised on polycrystalline silicon layers. The polysilicon films are deposited by the low pressure chemical vapour deposition (LPCVD) method on silicon oxide. The reverse current-bias characteristics and the breakdown voltage are plotted and analysed for different temperatures. It is shown that at low temperature, the current is due to tunnelling. This can be explained by the ionisation of traps localised in grains boundaries. At high temperature, electrical conduction is controlled by thermal emission. It is also shown that the breakdown voltage decreases when the temperature increases.