The demonstrated HgTe QD/graphene phototransistor device concept is accompanied by three main advantages (i) the spectral sensitivity can be tuned by the QD material, (ii) the phototransistor can be patterned by precise, local deposition of the QDs, as required for multicolor photodetectors, and (iii) the phototransistor can directly be fabricated on silicon-based substrates with robust phototransistor performance upon thermal cycling. Such a HgTe QD/graphene phototransistor shows similar spectral sensitivity, yet inferior specific detectivity, compared to commercial InAs detectors (specific detectivity of 8×10 Jones at a temperature of 77 K). It is important to note that there is an ample space to further optimize the HgTe QD/graphene phototransistors. For example, an improved specific detectivity is expected by QD deposition over the complete graphene channel, and at an optimized QD layer thickness.