期刊
NANO LETTERS
卷 17, 期 11, 页码 6954-6960出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.7b03414
关键词
AlN; nanowires; intersubband transition; photocurrent spectroscopy; IR photodetector; GaN
类别
资金
- EU ERC Starting Grant TeraGaN [278428]
- COSMOS project of the French National Research Agency [ANR-12-JS10-0002]
- French National Research Agency via the GaNeX program [ANR-11-LABX-0014]
- European Research Council (ERC) [278428] Funding Source: European Research Council (ERC)
Intersubband optoelectronic devices rely on transitions between quantum-confined electron levels in semiconductor heterostructures, which enables infrared (IR) photodetection in the 1-30 mu m wavelength window with picosecond response times. Incorporating nanowires, as active media could enable an independent control over the electrical cross-section of the device and the optical absorption cross-section. Furthermore, the three-dimensional carrier confinement in nanowire heterostructures opens new possibilities to tune the carrier relaxation time. However, the generation of structural defects and the surface sensitivity of GaAs nanowires have so far hindered the fabrication of nanowire intersubband devices. Here, we report the first demonstration of intersubband photodetection in a nanowire, using GaN nanowires containing a GaN/AlN superlattice absorbing at 1.55 mu m . The combination of spectral photocurrent measurements with 8-band k.p calculations of the electronic structure supports the interpretation of the result as intersubband photodetection in these extremely short-period superlattices. We observe a linear dependence of the photocurrent with the incident illumination power, which confirms the insensitivity of the intersubband process to surface states and highlights how architectures featuring large surface-to-volume ratios are suitable as intersubband photodetectors. Our analysis of the photocurrent characteristics points out routes for an improvement of the device performance. This first nanowire based intersubband photodetector represents a technological breakthrough that paves the way to a powerful device platform with potential for ultrafast, ultrasensitive photodetectors and highly efficient quantum cascade emitters with improved thermal stability.
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