Cation-Exchange-Derived Wurtzite HgTe Nanorods for Sensitive Photodetection in the Short-Wavelength Infrared Range

HgTe nanocrystals are one of the most promising candidates for optoelectronic applications in short- and middle-range infrared wavelength regions. Fabrication of one-dimensional anisotropic HgTe nanoparticles with a wurtzite structure has been a challenging task, so far. We introduce a two-step cation-exchange strategy to synthesize wurtzite-phase HgTe nanorods, starting from CdTe nanorods and proceeding through the formation of a Cu2–x Te intermediate. We demonstrate a means to tune the residual Cu content in the final HgTe nanorods from tens to less than one at % by adjusting the oleylamine and N,N-dimethylethylenediamine concentrations used during the Cu-to-Hg cation-exchange step. The photoluminescence peak position of the HgTe nanorods is tunable in the broad spectral range from 1500 to 2500 nm with the decrease of the residual Cu content. Field-effect transistors based on fabricated HgTe nanorods show favorable transport characteristics, namely, hole mobilities up to 10–2 cm2V–1 s–1 and on/off current ratio up to 103. The responsivity of photodetectors based on HgTe nanorods at 1340 nm reaches 1 A/W, and the detectivity is up to 1010 Jones for the devices with a simple planar geometry. Results presented here indicate wide prospects for exploring the electronic properties of wurtzite HgTe nanorods, as well as cation-doping and ligand surface passivation effects on device performance, which is of great importance for the field of modern optoelectronics.