Open AccessImprovement on performance of Si-based Ge PIN photodetector with Al/TaN electrode for n-type Ge contact
Author(s) -
Wei Zheng,
Wang Chen,
Guangxuan Yan,
Guanzhou Liu,
Li Cheng,
Wei Huang,
Hongkai Lai,
Songyan Chen
Publication year - 2012
Publication title -
wuli xuebao
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.199
H-Index - 47
ISSN - 1000-3290
DOI - 10.7498/aps.61.186105
Subject(s) - photodetector , materials science , responsivity , contact resistance , electrode , optoelectronics , passivation , dark current , silicon , layer (electronics) , nanotechnology , physics , quantum mechanics
Large contact resistance due to Fermi level pinning effect at the interface between metal and Ge strongly restricts the 3 dB bandwidth of Ge photodetectors. In this paper, the Ge PIN photodetectors fabricated on silicon-on-insulator substrates, respectively, with Al and Al/TaN electrodes are comparatively studied. It is found that 3 dB bandwidth of photodetector with 24 μm mesa diameter using an Al/TaN stack electrode is improved by four times more than that of the same structure Ge PIN photodetector using an Al electrode under -1 V bias at 1.55 μ. In addition, the dark current is reduced by one order of magnitude, and optical responsivity is enhanced by two times. These results suggest that a thin metallic TaN layer as an electrode can effectively passivate the Ge surface and alleviate the Fermi-level pinning effect, thus reducing the contact resistance and the recombination current at the interface. TaN can be considered as a promising electrode material for Ge device applications.