4.7 Article

MBE-Grown Hybrid Axial Core-Shell n-i-p GaAsSb Heterojunction Ensemble Nanowire-Based Near-Infrared Photodetectors up to 1.5 μm

Journal

CRYSTAL GROWTH & DESIGN
Volume 22, Issue 10, Pages 6004-6014

Publisher

AMER CHEMICAL SOC
DOI: 10.1021/acs.cgd.2c00652

Keywords

GaAsSb; MBE; core-shell nanowires; n-i-p heterojunction

Funding

  1. U.S. Army [W911NF-19-1-0002]
  2. National Science Foundation [ECCS-1542174, ECCS-1832117]

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In this paper, high-performance self-assisted molecular beam epitaxy (MBE)-grown conventional core-shell (C-S) n-i-p GaAsSb nanowires (NWs) and a novel hybrid axial C-S n-i-p GaAsSb ensemble NW-based near-infrared photodetector (NIRPD) on nonpatterned Si substrate are demonstrated. The conventional C-S n-i-p GaAsSb NW exhibits a high responsivity and detectivity, while the hybrid axial C-S n-i-p GaAsSb has band-gap-engineered for a longer wavelength. The findings suggest the potential of the hybrid axial C-S NW architecture in expanding the applications of IRPD and other optoelectronic devices.
In this paper, high-performance self-assisted molecular beam epitaxy (MBE)-grown conventional core-shell (C-S) n-i-p GaAsSb nanowires (NWs) and a novel hybrid axial C-S n-i-p GaAsSb ensemble NW-based near-infrared photodetector (NIRPD) on nonpatterned Si substrate are demonstrated. The conventional room-temperature (RT) C-S n-i-p GaAsSb NW with a high responsivity of 190 A/W and a higher detectivity of 1.1 x 10(14) Jones at -1 V bias and wavelength of 1.1 mu m is reported by optimizing the intrinsic region thickness and appropriately compensating the intrinsic p-type behavior with n-dopant Te. Furthermore, hybrid axial C-S n-i-p GaAsSb has been band-gap-engineered for wavelength up to 1.5 mu m, exhibiting responsivity of 18 A/W and detectivity of 1.1 x 10(13) Jones operating at RT. In this hybrid design, we have combined both axial and radial intrinsic (i-) segments of different Sb% compositions to enhance the photoabsorption in the NIR region; hence, the photogenerated current and also the high-band-gap axial i-region help to suppress the trap-assisted tunneling mechanism, which is found to be advantageous over conventional C-S NW architectures. In addition, high rectification ratio from current-voltage (I-V) measurements, suppression of low-frequency noise, lack of 1/f noise, a low corner frequency of similar to 2.5 Hz beyond which there is the presence of only frequency-independent white noise from low-frequency noise (LFN) measurements, and bias- and frequency-dependent capacitance-voltage (C-V) measurements suggest the formation of a high-quality C-S junction in the hybrid structure. Thus, our findings reveal that the hybrid axial C-S NW architecture provides the flexibility of three-dimensional (3D) design, which offers an unprecedented prospect for expanding IRPD and other next-generation optoelectronic device applications.

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