Be-doping assessment in Self-Catalyzed MBE Grown GaAs Nanowires

Ramaswamy, Priyanka; Pokharel, Rabin; Parakh, Mehul; Jones, K. M.; Li, Jia; Iyer, Shanthi

doi:10.1364/cleo_si.2021.sw2f.7

Cited by 5 publications

(5 citation statements)

References 5 publications

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“…Based on the axial growth rate of each segment, the overall segment growth duration was determined. In the growth of GaAsSb p-i-n NWs, gallium telluride (GaTe) captive source at the source temperature of 520 °C was used to achieve the carrier concentration of ∼5 × 10 18 cm −3 [24,25] and beryllium (Be) was used as a p-dopant at the source temperature of 920 °C to achieve the dopant concentration of 5 × 10 17 cm −3 [26,27]. During the i-segment growth, the intrinsic p-type nature of i-GaAsSb NWs is compensated by the intermittent supply of Te using a GaTe captive source, as Te being a group VI element is found to be a well-behaved n-type dopant [24,25,28] replacing group V elements, As and Sb, at low growth temperatures.…”

Section: Methodsmentioning

confidence: 99%

Heterostructure axial GaAsSb ensemble near-infrared p–i–n based axial configured nanowire photodetectors

et al. 2023

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In this work, we present a systematic design of growth experiments and subsequent characterization of self-catalyzed molecular beam epitaxially grown GaAsSb heterostructure axial p-i-n nanowires (NWs) on p-Si <111> for the ensemble photodetector (PD) application in the near-infrared (NIR) region. Diverse growth methods have been explored to gain a better insight into mitigating several growth challenges by systematically studying their impact on the NW electrical and optical properties to realize a high-quality p-i-n heterostructure. The successful growth approaches are Te-dopant compensation to suppress the p-type nature of intrinsic GaAsSb segment, growth interruption for strain relaxation at the interface, decreased substrate temperature to enhance supersaturation and minimize the reservoir effect, higher bandgap compositions of the n-segment of the heterostructure relative to the intrinsic region for boosting the absorption, and the high-temperature ultra-high vacuum in-situ annealing to reduce the parasitic radial overgrowth. The efficacy of these methods is supported by enhanced photoluminescence (PL) emission, suppressed dark current in the heterostructure p-i-n NWs accompanied by increased rectification ratio, photosensitivity, and a reduced low-frequency noise level. The PD fabricated utilizing the optimized GaAsSb axial p-i-n NWs exhibited the longer wavelength cutoff at ~ 1.1 µm with a significantly higher responsivity of ~ 120 A/W (@-3 V bias) and a detectivity of 1.1 ×10^13 Jones operating at room temperature. Frequency and the bias independent capacitance in the pico-Farad (pF) range and substantially lower noise level at the reverse biased condition, show the prospects of p-i-n GaAsSb NWs PD for high-speed optoelectronic applications.

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Section: Methodsmentioning

confidence: 99%

Heterostructure axial GaAsSb ensemble near-infrared p–i–n based axial configured nanowire photodetectors

et al. 2023

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“…% to tune the absorption wavelengths in the APD structure from 0.95 to 1.3 μm, corresponding to a band gap PL emission range of ∼1.25 to ∼0.95 eV (Supporting S1c). An optimum doping concentration and segment thickness were extracted from E -field simulations (using COMSOL Multiphysics) of the structures of varying segment thicknesses and doping profiles (Supporting S2) that would provide E -field strength >1 × 10 5 V/cm in the multiplication region to initiate the avalanche mechanism. , The doping density of each segment was calculated experimentally using a combination of X-ray photoelectron spectroscopy/ultraviolet photoelectron spectroscopy (XPS/UPS) and conductive atomic force microscopy (C-AFM)/scanning Kelvin probe microscopy based on our earlier work by Ramaswamy et al. , and Devkota et al The Be- and Te-doping density of different segments was estimated using a combination of XPS/UPS, , from quantifying the corresponding shift in the Fermi level toward the valance and conduction bands, respectively. These values were further confirmed from electron/hole densities computed from I – V characteristics of C-AFM measurements of the single nanowire (SNW).…”

Section: Methodsmentioning

confidence: 99%

GaAs/GaAsSb Core–Shell Configured Nanowire-Based Avalanche Photodiodes up to 1.3 μm Light Detection

Pokharel

Kuchoor

Parakh

et al. 2023

ACS Appl. Nano Mater.

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We report the first study on a GaAs/GaAsSb core−shell (CS)-configured nanowire (NW)-based separate absorption, charge control, and multiplication region avalanche photodiode (APD) operating in the near-infrared (NIR) region. Heterostructure NWs consisted of GaAs and tunable band gap GaAs 1−x Sb x serving as the multiplication and absorption layers, respectively. A doping compensation of absorber material to boost material absorption, segment-wise annealing to suppress trap-assisted tunneling, and an intrinsic i-type and n-type combination of the hybrid axial core to suppress axial electric field are successfully adopted in this work to realize a room-temperature (RT) avalanche photodetection extending up to 1.3 μm. In an APD device operating at RT with a unity-gain responsivity of 0.2−0.25 A/W at ∼5 V, the peak gain of 160 @ 1064 nm and 18 V reverse bias, gain >50 @ 1.3 μm, are demonstrated. Thus, this work provides a foundation and prospects for exploiting greater freedom in NW photodiode design using hybrid axial and CS heterostructures.

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“…18–21) in the absorption region. GaTe and Be source materials were used for segmental doping at 540 °C and 925 °C, yielding n-type doping ∼ 10 18 /cm −3 and p-type doping ∼ 5 × 10 17 /cm −3 , 22 respectively. A p + -contact layer with Be cell temperature of 925 °C and a group V/III flux ratio of 10 was used for ∼4 at% Sb incorporation in the segment.…”

Section: Methodsmentioning

confidence: 99%

Ensemble GaAsSb/GaAs axial configured nanowire-based separate absorption, charge, and multiplication avalanche near-infrared photodetectors

et al. 2022

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Be-doping assessment in Self-Catalyzed MBE Grown GaAs Nanowires

Abstract: We report on the Be-dopant assessment in Ga-assisted molecular beam epitaxially grown nanowires using conductive-atomic force microscopy, X-ray photoelectron spectroscopy, and ultraviolet photoelectron spectroscopy.

Cited by 5 publications

References 5 publications

Heterostructure axial GaAsSb ensemble near-infrared p–i–n based axial configured nanowire photodetectors

Heterostructure axial GaAsSb ensemble near-infrared p–i–n based axial configured nanowire photodetectors

GaAs/GaAsSb Core–Shell Configured Nanowire-Based Avalanche Photodiodes up to 1.3 μm Light Detection

Ensemble GaAsSb/GaAs axial configured nanowire-based separate absorption, charge, and multiplication avalanche near-infrared photodetectors

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