The forward current-voltage characteristic and forward capacitance-voltage characteristic measurements are the most important methods to study the forward electrical characteristic of light-emitting diodes.These methods can be used to characterize the properties of light-emitting diodes.To further understand p-n junction characteristics of light-emitting diodes

a novel method for measuring p-n junction was proposed.A direct current electrical source was used to charge the junction capacitance of light-emitting diodes

and the voltage-time characteristics of light-emitting diode was measured when the direct current electrical source was switched off.If the changed voltage is lower than the threshold voltage of light-emitting diodes

the voltage-time characteristics of light-emitting diodes is like the general diodes.If the charged voltage of is higher than the carrier recombination and emitting light threshold voltage of light-emitting diode

firstly

there is a fast voltage drop down process on the moment of discharge.The end voltage of drop down process is lower than the threshold voltage of light-emitting diodes.If the charged voltage of light-emitting diode is higher

then the end voltage of drop down process is lower.Some new conclusions can be obtained by analysing the discharge phenomena of light-emitting diodes.In fact

the non-equilibrium carriers which infused into the diffusion layer will be recombined and result in the formation of current when the direct changed voltage was switched off.The voltage-time characteristics of light-emitting diodes that we measured and observed reflect the recombination and attenuation process of the non-equilibrium carriers.By the theoretical analysis

we conclude that the non-equilibrium carriers will be less when the direct charged voltage is higher than the threshold voltage.The reason of this phenomenon needs further research.