【摘要】 利用正向交流(ac)小信号方法对发光二极管(LED)的电容-电压特性进行测量,可以观察到发光二极管中的负电容现象。通过对复合发光机理和发光二极管p-n结进行分析,得到了发光二极管在特定的正向电压范围内,由于发光概率复合急剧变化出现了dQ/dU<0的现象;当dQ/dU<0时,分析发光二极管结电容在正向偏压下对交流小信号的响应得到发光二极管表观电容的电流相位落后交流小信号电压相位π2,发光二极管表观电容表现为一个负电容。首次得到了发光二极管负电容与复合发光的关系表达式。更多还原

【Abstract】 The measurements of forward current-voltage characteristic and forward capacitance-voltage characte-ristic are the most important methods to study the forward electricity characteristic of light-emitting diodes. Forward alternating current (ac) small signal method can be used to measure the capacitance-voltage characteristic of light-emitting diodes,and negative capacitance can be observed. By analyzing the responds of light-emitting diodes junction capacitance by the alternating current small signalmethod based on forward direct current,we found that the current phase of apparent capacitance is behind the phase of voltage π2 when dQdU <0,leading to apparent capacitance being negative capacitance in measurement. Additionally,the expression of the negative capacitance in LED related with the recombination emitting is firstly obtained. By analyzing the responds of variable capacitance to the alternating current small signal,we also found that the variable capacitance for the specific parameter can make the phase of current be behind the phase of voltage,leading to the negative capacitance in measurement. The result of theory analysis tallies with the experiment. It was found the negative capa-citance is valuable for study the electrical characteristics of light-emitting diodes and valuable for the knowledge to improve the characteristic and parameter relevant the p-n junction internal structure of light-emitting diodes.更多还原