Graphene on Self-Assembled InGaN Quantum Dots Enabling Ultrahighly Sensitive Photodetectors

Highly sensitive photodetection is indispensable in applications, such as remote sensing, imaging, and smoke alarming. III-V nitrides are promising candidates for photodetectors due to their continuously tunable bandgap, radiation hardness, and temperature stability. However, the sensitivity of traditional III-V nitride-based photodetectors is limited by poor crystal quality which stems from lattice mismatch-induced point defects and dislocations. Recently, a new type of graphene-colloidal quantum dot (QD) hybrid phototransistor has been preferentially used to obtain high detection sensitivity, but III-V nitride-based colloidal QDs are hard to synthesize. Here, a highly sensitive QD/graphene hybrid photodetector is demonstrated by using self-assembled InGaN QDs. The photoconductance in the 2D graphene sheet is tuned by photogenerated carriers in the quantum dots when illuminated, and this effect leads to a current gain mechanism. The photodetector achieves an ultrahigh responsivity over 10(9) A W-1, a current gain of 10(9) and fW light detectivity even at room temperature. This study paves the way for new types of highly sensitive III-V nitride-based photodetectors despite the insufficient crystal quality.