Colloidal HgTe Quantum Dot/Graphene Phototransistor with a Spectral Sensitivity Beyond 3 µm

Infrared light detection enables diverse technologies ranging from night vision to gas analysis. Emerging technologies such as low-cost cameras for self-driving cars require highly sensitive, low-cost photodetector cameras with spectral sensitivities up to wavelength of 10 um. For this purpose, colloidal quantum dot (QD) graphene phototransistors offer a viable alternative to traditional technologies owing to inexpensive synthesis and processing of QDs. However, the spectral range of these phototransistors have been thus far limited to 1.6 um. Here, we present HgTe QD/graphene phototransistors with spectral sensitivities up to 3 um, with specific detectivities of 6x10⁸ Jones at a wavelength of 2.5 um and a temperature of 80 K. Even at kHz light modulation frequencies, specific detectivities exceed 10⁸ Jones making them suitable for fast video imaging. The simple device architecture and QD film patterning in combination with a broad spectral sensitivity manifest an important step towards low-cost, multi-color infrared cameras.