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分析了崖层在单行载流子光电探测器(UTC-PD)中的作用,以及其对UTC-PD的3dB带宽的影响。研究结果表明,崖层使得异质结处电场强度增加,且电场向吸收区延伸,使电子在吸收区的渡越时间和积累程度降低,从而导致3dB带宽和饱和电流增加;崖层的掺杂浓度和厚度都会对3dB带宽产生显著的影响;当崖层厚度与掺杂浓度的乘积一定,且收集区保持耗尽时,随着崖层厚度的增加(掺杂浓度减小),3dB带宽下降,但是,只要崖层的厚度不是太厚(通常为十几纳米到几十纳米),则无论是改变崖层厚度,还是改变掺杂浓度,3dB带宽的下降都可以忽略不计,即3dB带宽基本相等。
The role of the cliff in a single-line carrier photodetector (UTC-PD) and its effect on the 3dB bandwidth of UTC-PD are analyzed. The results show that the increase of the electric field intensity at the heterojunction and the extension of the electric field to the absorption zone lead to the decrease of the transit time and accumulation of electrons in the absorption zone, which leads to the increase of 3dB bandwidth and saturation current. Both the concentration and the thickness have a significant effect on the 3dB bandwidth. When the product of the thickness of the cliff and the doping concentration is constant and the collection area remains depleted, the 3dB bandwidth decreases as the thickness of the cliff increases (the doping concentration decreases) However, as long as the thickness of the cliff is not too thick (usually a few tens of nanometers to tens of nanometers), the drop in 3dB bandwidth is negligible regardless of the thickness of the cliff or the doping concentration, ie, the 3dB bandwidth is basically equal.