Measurement Of Forward Electrical Characteristics In Laser Diodes

As one of the most fundamental and important semiconductor devices, it is self-evident that the semiconductor laser diodes are widely used in many fields. So the research on electrical characteristics of semiconductor diodes has been a valuable subject since earlier time. In this paper, our work and achievement can be mainly summarized as follows:1 We improved data processing programmer for charactering the electrical behaviors and applied it to laser diodes. And we compared the results by using a.c. small signal analysis and those by the technique of electrical derivative. Large numbers of experiments confirmed that our measurement is an extraordinarily valid method for obtaining the electrical parameters of laser diodes in their working state. The outstanding point of our method is that it can character the function relations of the electrical parameters and the voltages or currents in detail.2 A lot of diodes have been measured. During the forward a.c, experiments, we observed that, just at the lasing threshold, the apparent conductance, the apparent capacitance and the apparent resistance all appear obvious discontinuities. Our lots of experiments confirmed this discontinuity is prevalent phenomenon in laser diodes, and it can be used to determine the threshold of a laser diode.3 A fact is observed that there is a discontinuity appearing in the vicinity of the lasing threshold before junction voltage reaches saturation. Discontinuity in series resistance, ideality factor, and junction capacitance occurs also corresponding to that of junction voltage. Combining with the electrical derivative characteristic, these discontinuities should be a fact that the laser diodes behave themselves in the vicinity of the lasing threshold. We also observed that the junction capacitance appears negative at large voltages and low frequencies.After the threshold, the experiment results of the junction voltage saturation...