Long‐Term, High‐Voltage, and High‐Temperature Stable Dual‐Mode, Low Dark Current Broadband Ultraviolet Photodetector Based on Solution‐Cast r‐GO on MBE‐Grown Highly Resistive GaN

Abstract

materials to form heterostructures due to the improved functionality of electronic and optoelectronic devices. [1][2][3][4][5][6] The 2D material-based devices can have a revolutionizing impact on technology covering from vacuum photodetection and photovoltaics to optical modulators and high speed data communication. [7][8][9][10][11][12][13][14][15][16] Predominantly through vertical transport of photogenerated carriers, the hybrid structures allow us to overcome the inherent persistent photoconductivity (PPC), where photocurrent of the host material generally persists for a long duration even after the illumination is removed, generally observed in the compound III-nitride semiconductor materials. [17][18][19][20][21] Usually PPC occurs due to the presence of donor and acceptor states closer to the conduction band minimum (CBM) and valence band maximum (VBM), which provides a large number of electron and hole trap states in the host material, respectively. Alternatively, with an introduction of intrinsic semiconductor materials, the PPC could be reduced as the donor and acceptor states show a shift from the CBM and VBM edges toward the midgap positions, which facilitate fast recombination time in comparison to the transit time of photo generated carriers through host materials. This has resulted in high speed operation in photoconductive mode. [22] In particular, GaN integrated with reduced-graphene oxide (r-GO) is a promising heterostructure for achieving improved device characteristics such as low dark current, high spectral responsivity, and high response speed. [17] 2D r-GO makes an optically active heterojunction with GaN. The emphasis so far has been given on r-GO/GaN heterostructure operating in the photovoltaic mode where the photogenerated carriers are swiftly swept across the depletion region predominantly via vertical transport. However, in the photoconductive mode operation, where the photogenerated carriers traverse across the host materials under the influence of an external bias exceeding the built-in-field of the heterostructure device, suffers either from high leakage current and/or PPC due to inherently negatively charged defects rich GaN. [23] The intentional/unintentional doping of suitable species can cause compensation of free New generation of hybrid photodetectors may provide the optimal solution for compact, highly sensitive, durable, and reliable broadband ultraviolet (BUV) sensors. A high-performance dual-mode BUV photodetector based on melding of highly resistive GaN and reduced graphene oxide is reported. Under zero bias, the device exhibits a sub-picoampere dark current, high light-to-dark current (I Light /I Dark ) ratio of ≈3.8 × 10 3 and high BUV-visible rejection ratio (≈1.8 × 10 2 ) with fast rise and fall times. The photodetector displays remarkable stability when subject to extreme operating conditions. The photoresponse of the detector shows a dark current of ≈2.41 nA at ± 200 V bias, I Light /I Dark ratio of ≈200 and high BUV-vis rejection ratio (≈7 × 10 2 ). The response ...

Ordered GaN Nanorod Arrays for Self-Powered Photoelectrochemical Ultraviolet Photodetectors

“…Remarkably, by fitting the photocurrent densities and light intensities, a linear relationship could be obtained, as shown in Figure 3b, suggesting that the device has a great linear response to UV light. To assess the capability of a PD responding to and detecting an optical signal from an atmospheric environment, the responsivity (R λ ) and detectivity (D*) were calculated using the following equations: 42,43…”

“…Remarkably, by fitting the photocurrent densities and light intensities, a linear relationship could be obtained, as shown in Figure b, suggesting that the device has a great linear response to UV light. To assess the capability of a PD responding to and detecting an optical signal from an atmospheric environment, the responsivity ( R λ ) and detectivity ( D *) were calculated using the following equations: , where P , S , e , and I dark represent the light intensity, effective illumination area, elementary charge, and dark current density, respectively. The calculated light-intensity-dependent R λ and D * are plotted in Figure c.…”

Photovoltaic Photodetectors Based on In2O3/InN Core–Shell Nanorods

“…The decrease in the distribution of the interface state density at the In 2 O 3 /InN NRs interface would be beneficial for the enhancement of charge carrier separation and extraction in In 2 O 3 /InN core–shell NRs. Apparently, the I – V results of In 2 O 3 /InN NRs and pristine InN are different, and Termann’s method is widely reported for the interface states density evolution in semiconductor device physics …”

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

“…The most important criterion in the selection of materials for high-performance photodetector (PD) is the exhibited photocarrier lifetime that should be long enough so the photocarriers can diffuse and drift to the respective electrodes before recombining. This has led to the integration of the suitable mixed dimensional materials to form hybrid heterojunction devices in order to achieve high performance. , The layered 2D material can be integrated with various dimensionalities to form mixed-dimensional heterojunction, such as 0D/2D, , 1D/2D, , 2D/2D, and 2D/3D − reported earlier for high-performance heterojunction devices. Among them, the amalgamation of 2D layered materials and conventional 3D semiconductors is the most exciting scheme because of stronger light matter interaction and easy integration with the established 3D semiconductor materials technology. − For such cases of 2D/3D devices, the top 2D layered material enhances the light-matter interaction through strong light absorption; in addition, the physical separation between the electrons and holes by the interfacial barrier of the heterojunction leads to prompt transportation of carriers.…”

“…Although r-GO provides the ease of forming efficient large-area devices using simple solution process techniques as compared to Graphene, little attention has been paid so far. Only few reports exploring the r-GO/GaN junction are available until date. ,− Prakash et al. demonstrated the use of r-GO as transparent electrodes to achieve fast response and recovery speed in GaN UV PD .…”