A study of n-doping in self-catalyzed GaAsSb nanowires using GaTe dopant source and ensemble nanowire near-infrared photodetector

Abstract

This work reports a comprehensive investigation of the effect of gallium telluride (GaTe) cell temperature variation (TGaTe) on the morphological, optical, and electrical properties of doped-GaAsSb nanowires (NWs) grown by Ga-assisted molecular beam epitaxy (MBE). These studies led to an optimum doping temperature of 550 °C for the growth of tellurium (Te)-doped GaAsSb NWs with the best optoelectronic and structural properties. Te incorporation resulted in a decrease in the aspect ratio of the NWs causing an increase in the Raman longitudinal optical/transverse optical vibrational mode intensity ratio, large photoluminescence emission with an exponential decay tail on the high energy side, promoting tunnel-assisted current conduction in ensemble NWs and significant photocurrent enhancement in the single nanowire. A Schottky barrier photodetector (PD) using Te-doped ensemble NWs with broad spectral range and a longer wavelength cutoff at ∼1.2 µm was demonstrated. These PDs exhibited responsivity in the range of 580–620 A W−1 and detectivity of 1.2–3.8 × 1012 Jones. The doped GaAsSb NWs have the potential for further improvement, paving the path for high-performance near-infrared (NIR) photodetection applications.

Epitaxial High-Yield Intrinsic and Te-Doped Dilute Nitride GaAsSbN Nanowire Heterostructure and Ensemble Photodetector Application

“…22 A doping concentration in the low 10 19 cm −3 range is estimated based on a reference GaAsSb material system. 22 Figure 4a represents dilute N Te-doped NWs (which shall be referred to as Te-BN hereafter) with an increased diameter of ∼215 nm, which is a strong indication of incorporation of Te, consistent with our earlier work by Ahmad et al 23 Dense NWs of 5 × 10 8 /cm 2 , comparable with BN samples, were observed with decreased axial and increased radial growth rates of 112 and 7 nm/min, respectively. A 9-fold and 4-fold increase in the emission peak intensity was observed in the RT and 4 K PL spectrum, respectively (shown in Figure 4b,c), which corroborates the increase in the free charge carrier density as a result of doping.…”

“…The optimization of the dopant temperature using the GaTe captive source was based on achieving the lowest ratio of dark current to photocurrent in the reference samples 7R shown elsewhere. 22 A doping concentration in the low 10 19 cm −3 range is estimated based on a reference GaAsSb material system. 22 Figure 4a represents dilute N Te-doped NWs (which shall be referred to as Te-BN hereafter) with an increased diameter of ∼215 nm, which is a strong indication of incorporation of Te, consistent with our earlier work by Ahmad et al 23 Dense NWs of 5 × 10 8 /cm 2 , comparable with BN samples, were observed with decreased axial and increased radial growth rates of 112 and 7 nm/min, respectively.…”

“…Next, doping of the NWs was examined using a GaTe captive source with the growth procedure adopted for sample BN. The optimization of the dopant temperature using the GaTe captive source was based on achieving the lowest ratio of dark current to photocurrent in the reference samples 7R shown elsewhere . A doping concentration in the low 10 19 cm –3 range is estimated based on a reference GaAsSb material system …”

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

“…5(b) ) at a low reverse bias of −1 V displays an S -curve behavior, characteristic of trap filling. 40 The invariant behavior of photocurrent with excitation power at a higher reverse bias of −6 V and −8 V further confirms the avalanche breakdown mechanism under illumination at −6 V, as discussed earlier in this section.…”

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

“…From the 4 K PL spectra and the LFN measurement, the G-R noise below the corner frequency is attributed to the presence of shallow traps. 25 The biasdependent C−V characteristic of the MI NW sample in Figure 7e displays a decrease in capacitance with the bias, though remaining positive in the frequency range of 10 kHz−1 MHz, to deep level traps and/or high resistivity of the intrinsic region. 35 Similar frequency dependence is observed in other pi-n junction-based materials, namely, 4H-SiC, 35 a-Si: H, 36 Si, 37 GaN, 38 and AlGaN.…”