A new method based on the series equivalent circuit of a diode was introduced to characterize the semiconductor diodes

through which the electrical characteristics such as the series resistance

the junction capacitance at forward bias

and the interfacial layer resistance and capacitance can be evaluated. By using this method

the p-n junction blue light emitting diodes (LEDs) fabricated by the wide-gap GaN semiconductor material were measured and analyzed

and the negative capacitance effect (NCE) of the GaN p-n junction diodes was observed and reported firstly. The negative capacitance appears more noticeable with the lower frequencies and the larger forward bias. It is found that the negative capacitance effect is constantly accompanied by the diode lighting. This phenomenon is explained by considering the electron-hole recombination lighting under high injection with large forward bias. The research on negative capacitance will be valuable for the improvement of the design

fabrication and characterization of the GaN semiconductor LEDs.