Houston, TX and Albuquerque, NM--A photodetector created by researchers from Rice University and Sandia National Laboratories has a spectral response that spans the visible to the mid-IR and is directly sensitive to polarization; the detector is based on p-n junctions formed between two macroscopic films of single-wall carbon nanotubes. Such detectors could be useful in astronomy, communications, and for military uses.
Rice’s new photodetector is the latest development from a collaboration between Rice and Sandia under Sandia’s National Institute for Nano Engineering program, which is funded by the U.S. Department of Energy.
In February, the group described a new method for making photodetectors from mats of carbon nanotubes. The nanotube mats used in the photodetectors are grown in the lab of Rice chemist Robert Hauge, who pioneered a process for growing densely packed nanotubes on flat surfaces. Xiaowei He, a graduate student in Kono’s group, found a way to use Teflon film to flatten these tightly packed nanotubes so that they are aligned in the same direction. Each mat contains dozens of varieties of nanotubes, and about two-thirds of the nanotubes are semiconductors.
Because each of the semiconducting nanotubes interacts with a specific wavelength of light, Kono’s team was able to show in its earlier work that the flattened, aligned mats could serve as broad-spectrum photodetectors. In the new study, lead author He uses dopants to create p-type and n-type mats; bringing the mats together creates p-n junctions.
The resulting detectors had a responsivity up to 1 V/W, which is about 35 times larger than for the devices without p-n junctions.
“Our work provides a new path for the realization of polarization-sensitive photodetectors that could be enabled on flexible or nonplanar surfaces,” He says.
The research was published in the American Chemical Society’s journal ACS Nano.
Source: http://news.rice.edu/2013/07/16/broadband-photodetector-for-polarized-light-2/
