Solution-Processed-2D on 3D Heterojunction UV–Visible Photodetector for Low-Light Applications

Abstract

We have demonstrated a heterojunction photodetector (PD) based on reduced graphene oxide (r-GO) and metal−organic chemical vapor deposition (MOCVD)-grown gallium nitride (GaN) that can sense very low light intensities in the above-band-gap and below-band-gap regimes, showing no and high photoconductive gains, respectively. The current− voltage characteristics of the device transforms from quasi photoconductive to photodiode behavior once the illumination wavelength is in the below-band-gap regime. The device exhibits a very low dark current of 0.85 pA at zero bias. In the selfpowered mode with low-light conditions (∼0.38 μW/cm 2 ) at 360 nm illumination, the light-to-dark current (I Light /I Dark ) ratio, responsivity (R λ ), specific detectivity (D*), and external quantum efficiency (EQE) of the fabricated PD were calculated to be ∼1 × 10 4 , 0.22 A/W, 1.486 × 10 14 Jones (cm Hz 1/2 W −1 ), and 77%, respectively. The response and recovery time of the PD were typically 485 and 886 μs, respectively under 280 Hz light switching frequency at zero bias. The device also shows significant photoconductive response with a typical persistent photoconductivity behavior at an applied bias of 5 V with extremely large I Light /I Dark ratio of ∼10 7 at 360 nm (∼0.15 mW/cm 2 ). The R λ , D*, and EQE were found to be 529 A/W, 4.25 × 10 16 Jones, and ∼2 × 10 5 %, respectively, for 360 nm illumination under low-light conditions (∼0.38 μW/cm 2 ), at 5 V applied bias. The extraordinary performance of the device in both photovoltaic and photoconductive modes makes r-GO/GaN heterojunction scheme suitable for dual-mode low-light UV−visible applications.

Ag Nanowire-Plasmonic-Assisted Charge Separation in Hybrid Heterojunctions of Ppy-PEDOT:PSS/GaN Nanorods for Enhanced UV Photodetection

“…Furthermore, to understand the excellent optoelectrical performances of photodetectors, the relationship between the photocurrent and power densities were well described using the power law, i.e., I ph α NP θ , which can be retrieved from the fitting plot, as shown in Figure a, − where I ph is the photocurrent value, N is the proportionality constant, P stands for light intensity, and θ is the empirical coefficient. The estimated nonunity exponent (θ) value from the fitting points was found to be 0.86 for M4.…”

“…To quantitatively investigate the gain mechanism and the optoelectronic efficiency conversion of PD, we have plotted a graph for responsivity ( R λ ) and external quantum efficiency (EQE), as shown in Figure b,c. The responsivity is related to the generated photocurrent per incident power density of light, where EQE is defined as the ratio of the number of excited electrons collected at electrodes to the incident photons, in which both are calculated using the following equations, respectively. ,, where Δ I are the differences in the photocurrent and the dark current (Δ I = I ph – I d ), P is the light power density, A is the effective illuminated area of the sample, h is Planks constant, c is the speed of light, e is the charge of an electron, and λ is the wavelength of the incident LED light. In accordance with both equations, one can observe that R λ and EQE were strongly dependent on light intensity.…”

MoSe2/n‐GaN Heterojunction Induced High Photoconductive Gain for Low‐Noise Broadband Photodetection from Ultraviolet to Near‐Infrared Wavelengths

“…[39][40][41][42] To date, there have been few research studies on GaN-based TMD hybrid heterostructure photodetectors that depict its capability for obtaining better response in UV region. [43][44][45][46][47][48][49][50][51][52][53] For instance, the responsivity of 24.6 A W −1 for MoS 2 on GaN photodetectors by introducing tensile strain on the heterostructure with the deposition of 3 nm Al 2 O 3 has been reported. [51] The wafer-scale growth of thin MoSe 2 films on GaN by using the chemical vapor deposition technique has been discussed.…”

Design of p‐WSe2/n‐Ge Heterojunctions for High‐Speed Broadband Photodetectors

“…[ 13 ] Therefore, an alternative strategy of stacking 2D materials with conventional 3D semiconductors has been adopted so that materials with high light absorption coefficients can be used based on phototransistor and photodiode device schemes. [ 14–18 ]…”

“…[13] Therefore, an alternative strategy of stacking 2D materials with conventional 3D semiconductors has been adopted so that materials with high light absorption coefficients can be used based on phototransistor and photodiode device schemes. [14][15][16][17][18] In vdW 2D/3D heterostructures, the region comprising the 3D semiconductor, which may include III-V compounds as well as group IV semiconductors can be controlled via a reliable and stable fabrication process. [19] Germanium (Ge) in group IV, which has a narrow bandgap of ≈0.7 eV, is promising not only for Infrared (IR) detection but also for complementary metal-oxide-semiconductor (CMOS)-compatible processes and designs.…”