Silicon/organic hybrid heterojunction infrared photodetector operating in the telecom regime

Abstract

Graphical abstract

Enhanced near-infrared response of nano- and microstructured silicon/organic hybrid photodetectors

“…Critical findings include that several different structurization techniques, providing structures spanning the range from 10 nm to 20 lm, all lead to substantial improvement in photocurrent generation over planar interface samples. Responsivity values in the telecom-relevant range, 1.3-1.6 lm, obtained with the best structured devices are between 1 and 2 mA/W at 0 V bias, increasing to around 5 mA/W at À1 V. These values are a 10-fold improvement over the previous best report of a pSi/organic NIR diode, 13 while preserving favorable diode characteristics. The mechanism of sensitization that is responsible for the NIR performance of p-Si/organic junctions remains elusive, which makes the interpretation of the substantial improvement given by the structured interfaces problematic.…”

“…18,19 The hotwall epitaxy technique we utilized was reported previously to give conformal Stranski-Krastanov films for a perylene bisimide derivative on flat Si substrates. 13 Relatively uniform and continuous coverage of the p-Si with TyP is critical in achieving optimal heterojunction diodes due to the passivation of surface states present at structured silicon surface, in order to avoid the carrier recombination and obtain low dark currents in reverse bias. Current density-Voltage (J-V) characteristics of the prepared photodiodes were measured in the dark and under illumination with a laser diode emitting at 1.48 lm with an intensity of 200 mW/cm 2 .…”

“…Further, it would be straightforward to expect the photocurrent enhancement to originate from increased interfacial area between p-Si and TyP, as this correlates directly with the two models for the NIR-absorption mechanism in these diodes, set forth in the literature: (1) a type-II heterojunction transition between the p-Si valance band and organic epilayer conduction band, 12 and (2) absorption by a surface state originating from reactivity of the Si surface and the organic molecular layer. 13,15 However, consideration of the increase in interfacial area also appears insufficient to account for the observed enhancement of photocurrent. For the l-pyramid samples which show the highest J SC enhancement, for example, the area increases by a factor of 1.55 (calculation based on 3D modeled surface as shown in supplementary material Fig.…”

“…Improved devices featuring a 20-30 nm-thick vacuum-evaporated organic layer on p-Si, followed this work. 13 With these improvements, and the exchange of C 60 for other organic small molecules such as indigo and perylene derivatives, the devices gave NIR responsivity around 1 Â 10 À4 A/W while operating at room temperature and were sensitive down to 2500 nm (0.49 eV). The diodes evaluated here are heterojunction devices between p-Si with micro-and nano-structured surface, and an organic semiconductor Tyrian Purple (6,6 0 -dibromoindigo) 14,15 (Figure 1(a)), operated at room temperature.…”

Carrier transport mechanisms and photodetector characteristics of Ag/TiOPc/p-Si/Al hybrid heterojunction

“…In recent years, many attempts have been made to integrate organic and inorganic semiconductors to form hybrid structures in order to take the advantages of each material [1][2][3]. In earlier reports, it has been shown that organic and inorganic hybrid combination has complementary advantages, such as high carrier mobility and wide absorption spectrum from the inorganic side, and low temperature solution processability and low cost processability from the organic side [4,5].…”