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

Abstract

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.

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

“…48 The compensation of the Sb absorber region and hence the increase in absorption efficiency were marked by a substantial increase in the responsivity and external quantum efficiency. 48 This sample with ∼10 at. % Sb incorporation in the absorption region combined with segment-wise annealing shall be referred to as S10 hereafter.…”

“…The i-GaAsSb layer segment was compensated with n-type Te-doping for 5 s over a 1 min interval to achieve lower intrinsic doping in the region. The details of compensation for the intrinsic p-nature of GaAsSb for the enhancement of absorption and material properties are discussed elsewhere . The compensation of the Sb absorber region and hence the increase in absorption efficiency were marked by a substantial increase in the responsivity and external quantum efficiency .…”

“…The details of compensation for the intrinsic p-nature of GaAsSb for the enhancement of absorption and material properties are discussed elsewhere. 48 The compensation of the Sb absorber region and hence the increase in absorption efficiency were marked by a substantial increase in the responsivity and external quantum efficiency. 48 This sample with ∼10 at.…”

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

“…In this work, we have examined conventional C–S n-i-p junction GaAsSb NWs (Figure a) grown by self-assisted molecular beam epitaxy (MBE) with variation in the intrinsic “i”- region width and a simple Te compensation approach to improve the device performance, as undoped GaAsSb is slightly p-type, which is attributed to residual acceptor impurity, namely, Ga vacancy-related defects and Ga antisite defects (V Ga Ga Sb ). , To reduce the background carrier concentration, n-dopant pulsing in the form of a GaTe source was introduced during the growth of the i-GaAsSb shell. We demonstrate the fabrication and characterization of MBE-grown room-temperature (RT) conventional devices for the application of near-IR photodetectors at wavelengths approaching 1.1 μm with high rectification ratio, enhanced responsivity and detectivity, and low series resistance.…”