Single GaAs Nanowire/Graphene Hybrid Devices Fabricated by a Position-Controlled Microtransfer and an Imprinting Technique for an Embedded Structure

Mukherjee, Anjan; Huang, Yun; Shin, Dong Hoon; Nam, Jungtae; Munshi, A. Mazid; Dheeraj, Dasa L.; Fimland, B. O.; Weman, H.; Kim, Keun Soo; Lee, Sang Wook; Kim, Dong Chul

doi:10.1021/acsami.8b20581

Cited by 9 publications

(7 citation statements)

References 39 publications

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“…As shown in Figure 6 , the band structures based on Anderson’s rule are used to clarify the physics behind the above-observed I-V characteristics of camphor-based CVD graphene/p-Si Schottky PDs [ 46 , 54 , 55 , 56 , 57 ]. Figure 6 a is the band structure of the camphor-based CVD graphene/p-Si heterostructure at thermal equilibrium under zero bias.…”

Section: Measurement Results and Discussionmentioning

confidence: 99%

Camphor-Based CVD Bilayer Graphene/Si Heterostructures for Self-Powered and Broadband Photodetection

et al. 2020

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This work demonstrates a self-powered and broadband photodetector using a heterojunction formed by camphor-based chemical vaper deposition (CVD) bilayer graphene on p-Si substrates. Here, graphene/p-Si heterostructures and graphene layers serve as ultra-shallow junctions for UV absorption and zero bandgap junction materials (<Si bandgap (1.1 eV)) for long-wave near-infrared (LWNIR) absorption, respectively. According to the Raman spectra and large-area (16 × 16 μm2) Raman mapping, a low-defect, >95% coverage bilayer and high-uniformity graphene were successfully obtained by camphor-based CVD processes. Furthermore, the carrier mobility of the camphor-based CVD bilayer graphene at room temperature is 1.8 × 103 cm2/V·s. Due to the incorporation of camphor-based CVD graphene, the graphene/p-Si Schottky junctions show a good rectification property (rectification ratio of ~110 at ± 2 V) and good performance as a self-powered (under zero bias) photodetector from UV to LWNIR. The photocurrent to dark current ratio (PDCR) value is up to 230 at 0 V under white light illumination, and the detectivity (D*) is 8 × 1012 cmHz1/2/W at 560 nm. Furthermore, the photodetector (PD) response/decay time (i.e., rise/fall time) is ~118/120 μs. These results support the camphor-based CVD bilayer graphene/Si Schottky PDs for use in self-powered and ultra-broadband light detection in the future.

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Section: Measurement Results and Discussionmentioning

confidence: 99%

Camphor-Based CVD Bilayer Graphene/Si Heterostructures for Self-Powered and Broadband Photodetection

et al. 2020

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“…Once this two-step cascaded etching profile is made (inspected with scanning electron microscopy after each step), single NWs were embedded in a curable photoresist layer through a resist etch-back method. This structure helps to form better electrical contacts in the planar single-NW configuration . Three different metal electrodes were then deposited successively to form separate electrical contacts to the outermost radial n ++ -GaAs cap, i-GaAs shell, and inner p-GaAs core separately at the top, middle, and bottom parts of the NW, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…This structure helps to form better electrical contacts in the planar single-NW configuration. 39 Three different metal electrodes were then deposited successively to form separate electrical contacts to the outermost radial n ++ -GaAs cap, i-GaAs shell, and inner p-GaAs core separately at the top, middle, and bottom parts of the NW, respectively. In this process, Pd (20 nm)/Ge (40 nm)/Au (250 nm), Ti (10 nm)/Au (250 nm), and Pt (5 nm)/Ti (10 nm)/Pt (10 nm)/Au (200 nm) metal electrodes were deposited to form ohmic electrical contacts to the n ++ -GaAs cap, i-GaAs shell, and p-GaAs NW core separately.…”

Section: Nanoprobing To Singlementioning

confidence: 99%

Origin of Leakage Currents and Nanowire-to-Nanowire Inhomogeneity in Radial p–i–n Junction GaAs Nanowire Array Solar Cells on Si

Mukherjee

Ren

Mosberg

et al. 2023

ACS Appl. Nano Mater.

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To realize the promising potential of radial junction nanowire (NW) array-based solar cells, it is crucial to get physical insight into how the overall photoconversion efficiency (PCE) is impacted by the hole mask properties, NW growth, and post-growth device processing. In this work, we have fabricated and analyzed a radial p−i−n junction GaAs NW array solar cell grown by molecular beam epitaxy (MBE) on a Si substrate. Multiple electrical measurements are correlated through a range of characterization techniques such as nanoprobing of as-grown individual NWs, multicontact single-NW studies, and structural characterization of the fabricated NW array solar cell. A relatively high leakage current density (∼120 mA/cm 2 at −1 V) was measured from the solar cell, resulting in a PCE of only ∼2.1%. The origin of this high leakage current was further investigated by measuring the electrical transport properties of individual as-grown NWs in the array through nanoprobing, revealing a high variation in electrical properties from NW to NW. In contrast to this, planar single-NW solar cells have shown rectifying characteristics with high on/off ratios and an average PCE of ∼5.2%, indicating a leakage path in the vertical configuration of the NWs. Furthermore, structural analysis of the NW array reveals a regular occurrence of NWs with off-centered nucleation for the p-GaAs NW core in the holes in the hole mask, leading to a partial or full electrical shortening of the n-GaAs NW shell to the p-Si substrate. This is shown to be predominantly responsible for the high leakage current density and poor PCE from the NW array solar cell. These findings will help to improve the structural design of radial junction NW array solar cells in order to further improve the PCE.

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“…After a successful etching of the shell, single NWs were partially embedded in a curable photoresist layer by employing a resist etch-back method using O 2 -plasma ashing . A planar embedded configuration of single NWs has recently been reported as a superior structure compared to a conventional nonembedded structure when an ohmic contact between a NW and its contact electrode is desired . Metal contact electrodes were fabricated to the shell-etched p- and n-parts of the NW by using two successive EBL and lift-off processes, where Pt (5 nm)/Ti (10 nm)/Pt (10 nm)/Au (150 nm) and Pd (20 nm)/Ge (40 nm)/Au (150 nm) metal stacks were deposited on the p- and n-sides of the NW, respectively. , All metal contacts were annealed at 280 °C for 30 s to form ohmic contacts between the NW and the metal electrodes. , …”

Section: Methodsmentioning

confidence: 99%

GaAs/AlGaAs Nanowire Array Solar Cell Grown on Si with Ultrahigh Power-per-Weight Ratio

et al. 2021

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Here we demonstrate a more effective use of III−V photoconversion material to achieve an ultrahigh power-per-weight ratio from a solar cell utilizing an axial p-i-n junction GaAs/AlGaAs nanowire (NW) array grown by molecular beam epitaxy on a Si substrate. By analyzing single NW multicontact devices, we first show that an n-GaAs shell is self-formed radially outside the axial p-and i-core of the GaAs NW during n-core growth, which significantly deteriorates the rectification property of the NWs in the axial direction. When employing a selective-area ex situ etching process for the n-GaAs shell, a clear rectification of the axial NW p-i-n junction with a high on/off ratio was revealed. Such a controlled etching process of the self-formed n-GaAs shell was further introduced to fabricate axial p-i-n junction GaAs NW array solar cells. Employing this method, a GaAs NW array solar cell with only ∼1.3% areal coverage of the NWs shows a photoconversion efficiency of ∼7.7% under 1 Sun intensity (AM 1.5G), which is the highest achieved efficiency from any single junction GaAs NW solar cell grown on a Si substrate so far. This corresponds to a power-perweight ratio of the active III−V photoconversion material as high as 560 W/g, showing great promise for high-efficiency and lowcost III−V NW solar cells and III−V NW/Si tandem solar cells.

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Single GaAs Nanowire/Graphene Hybrid Devices Fabricated by a Position-Controlled Microtransfer and an Imprinting Technique for an Embedded Structure

Cited by 9 publications

References 39 publications

Camphor-Based CVD Bilayer Graphene/Si Heterostructures for Self-Powered and Broadband Photodetection

Camphor-Based CVD Bilayer Graphene/Si Heterostructures for Self-Powered and Broadband Photodetection

Origin of Leakage Currents and Nanowire-to-Nanowire Inhomogeneity in Radial p–i–n Junction GaAs Nanowire Array Solar Cells on Si

GaAs/AlGaAs Nanowire Array Solar Cell Grown on Si with Ultrahigh Power-per-Weight Ratio

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