Characterization of dark current in Ge-on-Si photodiodes
Characterization of dark current in Ge-on-Si photodiodes
复制标题
Ge-on-Si 光电二极管中暗电流的表征
DOI：
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发表时间：
2012
期刊：
影响因子：
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通讯作者：
J. Hoyt
中科院分区：
文献类型：
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作者：
N. DiLello;D. Johnstone;J. Hoyt
用低压化学气相沉积方法生长了锗薄膜，制备了Ge-on-Si光电二极管。通过几何分析、随温度变化的电流-电压特性、深能级暂态光谱和器件模型研究了这些器件暗电流产生的机理。研究发现，漏电流的一个重要来源与表面耗尽区有关，而表面耗尽区受Ge/介质界面固定电荷性质的影响。这种泄漏源尤其影响面积较小的器件，大约为10 × 10 μm2。通过后金属化退火，这些器件的暗电流可以降低到∼1000倍。通过有意地在P型锗薄膜的顶部掺杂可以获得类似的还原。经过等离子体处理后，发现大尺寸器件的暗电流密度为∼1 mA/cm~2，主要原因是在器件的耗尽区产生了少数载流子。文中还讨论了降低穿丝位错密度的效果。
Ge-on-Si photodiodes were fabricated from germanium films grown using low-pressure chemical vapor deposition. The mechanisms responsible for the dark current in these devices are studied using geometric analysis, temperature-dependent current-voltage characterization, deep level transient spectroscopy, and device modeling. It is found that an important source of leakage current is associated with the surface depletion region, which is impacted by the nature of the fixed charge at the Ge/dielectric interface. This source of leakage especially affects devices with smaller area, on the order of 10 × 10 μm2. Through a post-metallization anneal (PMA), the dark current of these devices can be reduced by ∼1000X. A similar reduction can be obtained by intentionally doping the top of the germanium film p-type. After the PMA, it is found that the dark current density of large devices is ∼1 mA/cm2, due mainly to generation of minority carriers in the depletion region of the device. The effect of reducing the threading dislocation density is also discussed.