Ambipolar Graphene–Quantum Dot Phototransistors with CMOS Compatibility

Abstract

The hybridization of 2D materials and colloidal quantum dots (CQDs) has been demonstrated to be an ideal platform for infrared photodetectors due to the high mobility of 2D materials and the excellent light harvesting capability of CQDs. However, the realization of ambipolar, broadband, and room‐temperature graphene–quantum dot phototransistors with complementary metal–oxide–semiconductor (CMOS) compatibility remains challenging. Here N, S codecorated graphene is deposited with PbS CQDs to fabricate a hybrid phototransistor on a silicon dioxide/silicon gate. The resulting device demonstrates a gate‐tuneable ambipolar feature with a low gate bias of less than 3.3 V at room temperature in ambient. Broadband spectra from visible to near‐infrared and to short wave infrared (SWIR) light can be detected with gain value of up to 105 and a fast response of 3 ms. Upon illumination by SWIR light at 1550 nm, the phototransistor exhibits an ultrahigh responsivity that is on the order of 104 AW−1 and a specific detectivity that is on the order of 1012 Jones with a low driving voltage of 1 V. This decorated hybrid architecture illustrates the potential of graphene and CQDs to be integrated with silicon integrated circuits and opens a new path toward ambipolar photodetector fabrication.

Integrated Structure and Device Engineering for High Performance and Scalable Quantum Dot Infrared Photodetectors

“…To overcome this problem, N, S co-decorated graphene fabricated by chemical vapor deposition (CVD) was also deposited with PbS CQDs to fabricate a hybrid phototransistor with CMOS compatibility (Figure 9g). [77] P-type doping can be effectively inhibited by N, S co-decorating. As a result, the required gate voltage can be reduced to less than 3.3 V that is compatible with CMOS technology (Figure 9h).…”

Explicit Gain Equations for Hybrid Graphene‐Quantum‐Dot Photodetectors

“…Similar photoresponses were also observed in graphene/QD photodetectors by others. 14 When the gate voltage is far from the appeared Dirac point on the left side, the conductivity of the graphene device is linear with the gate voltage. A right shift in gate transfer characteristics will result in a constant increase in conductivity, i.e.…”

“…10,11,12,13 Coating graphene with semiconducting quantum dots (QDs) can strongly enhance the light absorption and introduce an interesting high photo gain at an order of 10 8 , 14, 15, 16 several orders of magnitude larger than photodetectors based on pure semiconducting QDs (often have a photo gain of 10 2 -10 3 ). 17,18,19 The classical carrier-recycling gain mechanism is often used to explain the origin of high gain, 14,15,16 that is, the high gain originates from the photoexcited carriers circulating the circuits many times before recombination due to the long response time and short transit time. 20 However, this classical gain theory is an implicit function and may even be questionable.…”

Room-temperature infrared photodetectors with hybrid structure based on two-dimensional materials

“…Similarly, Zheng et al demonstrated an ambipolar broadband photodetector based on N, S codecorated graphene-PbS quantum dot heterostructure. [42] N, S codecorated graphene greatly reduces the p-type doping of graphene in air. The gate voltage required to modulate the Dirac point and the carrier type is significantly reduced, thereby achieving gate tuneable mutual transformation of positive and negative photoresponse.…”