Large Electroabsorption Susceptibility Mediated by Internal Photoconductive Gain in Ge Nanowires
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- 作者：Hyun-Seung Lee ; Cheol-Joo Kim ; Donghun Lee ; Ru Ri Lee ; Kibum Kang ; Inchan Hwang ; Moon-Ho Jo
- 刊名：Nano Letters
- 出版年：2012
- 出版时间：November 14, 2012
- 年：2012
- 卷：12
- 期：11
- 页码：5913-5918
- 全文大小：441K
- 年卷期：v.12,no.11(November 14, 2012)
- ISSN：1530-6992
文摘
Large spectral modulation in the photon-to-electron conversion near the absorption band-edge of a semiconductor by an applied electrical field can be a basis for efficient electro-optical modulators. This electro-absorption effect in Group IV semiconductors is, however, inherently weak, and this poses the technological challenges for their electro-photonic integration. Here we report unprecedentedly large electro-absorption susceptibility at the direct band-edge of intrinsic Ge nanowire (NW) photodetectors, which is strongly diameter-dependent. We provide evidence that the large spectral shift at the 1.55 渭m wavelength, enhanced up to 20 times larger than Ge bulk crystals, is attributed to the internal Franz鈥揔eldysh effect across the NW surface field of 105 V/cm, mediated by the strong photoconductive gain. This classical size-effect operating at the nanometer scale is universal, regardless of the choice of materials, and thus suggests general implications for the monolithic integration of Group IV photonic circuits.