Enhancing the photoelectrical performance of graphene/4H-SiC/graphene detector by tuning a Schottky barrier by bias

Abstract

Graphene/4H-SiC/graphene photodetectors, as well as graphene/4H-SiC heterojunctions, have been fabricated and characterized by utilizing a heating decomposition method. High-quality graphene has been grown on an n− doped 4H-SiC substrate along with a 900 °C hydrogenation process. Temperature-dependent current–voltage characteristics of the graphene/4H-SiC heterojunction have been measured to obtain the Schottky barrier height. The bias-dependent Schottky barrier height (varying from 0.43 eV to 0.41 eV) was found and could result mainly from the electrical doping and Fermi level shifting in graphene. With the increase in the bias, the unsaturated dark current of graphene/4H-SiC/graphene photodetectors indicated the electron diffusion at the graphene/4H-SiC heterojunction. The increased responsivity peaks come from the absorption of the graphene layer in the UV range and the long lifetime of photo-induced thermal electronic carriers being contributed to the bandgap shrinking of graphene and reduction of the Schottky barrier height. The photodetectors biased at 6 V showed a responsivity of 40 A/W, an external quantum efficiency of 1.38 × 104%, and a detectivity of 9 × 1011 Jones, which are larger than those of previously reported similar devices based on graphene/SiO2 or graphene/SiC.

Resonant-cavity-enhanced 4H-SiC thin film MSM UV photodetectors on SiO2/Si substrates

“…Therefore, according to both simulations, the prepared SiCOI structure with a 1.05 µm thick 4H-SiC was fully depleted. On the other hand, UV detectors fabricated from homogenous epitaxy [17][18][19][20] (see table 1) all have 4H-SiC layers thicker than the simulated 2.3 µm longitudinal depletion depth, and therefore have significant amount of un-depleted thickness that only weakly contributes to the response and reduces the response speed of the device.…”

“…There are various research directions have been explored to enhance the performance of PDs. These include using antireflection layers to reduce the reflection of incident light [16], applying thermal annealing to reduce the dark current of the device [17], introducing localized surface plasmon resonance (LSPR) to improve light absorption [18], employing graphene electrodes to increase light incidence [19], and adding microhole arrays and localized surface plasmon resonance of Al nanoparticles on 4H-SiC MSM PDs [20].…”

High‐Performance SiC/Graphene UV‐Visible Band Photodetectors with Grating Structure and Asymmetrical Electrodes for Optoelectronic Logic Gate

“…[23,24] These properties make graphene a prominent candidate for future optoelectronic applications, including transparent electrodes, [25] surface plasmonic devices, [26] and multi-wavelength PDs. [27][28][29] Generally, graphene can be prepared by mechanical exfoliation, [30] liquid-phase exfoliation, [31] chemical vapor deposition (CVD), [32][33][34] and thermal decomposition of silicon carbide (SiC). [35] Fortunately, the fabrication of graphene on SiC by thermal decomposition has been proposed as a feasible approach to synthesize non-transfer uniform graphene layers, which are sensitive to both UV and visible range.…”

Metal–Semiconductor–Metal Ultraviolet Photodetectors Based on Al Nanoparticles in 4H-SiC Microholes

“…However, 4H-SiC PDs suffered from low responsivity and quantum efficiency properties because of the low UV light absorption efficiency. In recent years, in order to further improve the performance of PDs, many methods had been used to improve the absorption efficiency including antireflection film, semitransparent electrode, microlens, nanowires, nanoholes, and nanorods. , Microhole (MH) structure also has attracted much attention due to its facile preparation and high specific surface area under light conditions. Naderi et al investigated the MH formation of electrochemical corrosion SiC to enhance the detector performance .…”