| dc.description.abstract |
Compared with III-V photodetector, Silicon based photodetector has 10 to 100 times higher dark current, so decreasing dark current is an important topic. In the past, Silicon based component reduces the surface recombination rate through the passivation layer to achieve the purpose of reducing the dark current of the component. However, there is no passivation layer between the metal and semiconductor. In order to solve the above problems, A technology call ‘‘passivated contact’’ is proposed to reduce the carrier recombination between the metal and the semiconductor. This structure is inserted the ultra-thin passivation film between the metal and semiconductor, it can achieve a good passivation effect and the carrier can tunnel the passivation. Rencently, this structure is mostly used in solar cells, but the solar cell structure is similar to photodetector, so this propasal of this research is to investigate the passivated contact, and apply it to the silicon based photodetector to lower the dark current density.
The ultra-thin oxide layer is the key to passivated contact, so this study first grows the oxide layer in different methods and discusses its properties, and then stacks the silicon nitride on the oxide layer to enhance the overall passivation effect. The experimental results show that Through RTA annealing interval of 200 degrees to 800 degrees to enhance the passivation properties, the passivated contact can measure the maximum lifetime is 1515us, iVoc is 650mV at 400 degrees. In order to enhance the carrier transport capacity of this structure, we use dry etching to reduce the thickness of silicon nitride from 80nm to 15nm.
Finally, passivated contact is applied to the silicon-based photodetector. The experimental results show that the passivated contact of the silicon nitride and the oxide layer can reduce the dark current of the photodetector from 1.44x10-7 to 5.42x10-9 A, dark Current density of up to 1.93x10-5 mA/cm2. In addition, it was also investigated that indium tin oxide covered with this passivated contact structure and found that the component dark current was reduced to 5.36x10-9A, and the responsibility of 0.658 A / W at an operating bias of -5 V. | en_US |