Improved performance of GaAsSb/AlGaAs nanowire ensemble Schottky barrier based photodetector via in situ annealing

Abstract

In this work, we report on the p-i GaAsSb/AlGaAs nanowires (NWs) ensemble device exhibiting good spectral response up to 1.1 μm with a high responsivity of 311 A W, an external quantum efficiency of 6.1 × 10%, and a detectivity of 1.9 × 10 Jones at 633 nm. The high responsivity of the NWs has been attributed to in situ post-growth annealing of GaAsSb axial NWs in the ultra-high vacuum. The enabling growth technology is molecular beam epitaxy for the Ga-assisted epitaxial growth of these NWs on Si (111) substrates. Room temperature Raman spectra, as well as temperature dependent micro-photoluminescence peak analysis indicated suppression of band tail states and non-radiative channels due to annealing. A similar improvement in in situ annealed p-i GaAsSb NW ensemble with an AlGaAs passivating shell was inferred from a reduction in the Schottky barrier height as well as the NW resistance compared to the as-grown NW ensemble. These results demonstrate in situ annealing of nanowires to be an effective pathway for improving the optoelectronic properties of the NWs and the device thereof.

III–V ternary nanowires on Si substrates: growth, characterization and device applications

“…There are already reports that describe detailed characterizations and investigation of the optical properties of GaAsSb NWs on Si substrates grown via CVD [78] and MBE. [27][28][29]52,[79][80][81][82][83][84][85][86] As mentioned earlier, the Sb content, for structures grown on Si, is kept at a relatively low level. In several cases of growth on patterned Si substrates, where VLS growth occurred, the size of the pattern plays an important role in the morphology and elemental composition of the structures.…”

“…[84] To further improve surface passivation, core/shell structures can be grown, where AlGaAs has been used as shells to neutralize surface states. [28] for most of the papers mentioned so far, rendering the NWs Sb-poor. [27][28]79,[83][84][85] However, the significance of high wavelength emission for telecommunication applications and infrared light detections leads to concentrated efforts to increase the amount of Sb that is incorporated in the NWs.…”

“…The tuneable bandgap is also crucial for ternary NW-based photodetectors with comparable or even enhanced figures of merit when compared to devices based on binary NWs. [27][28] Another benefit in some ternary NWs is that the addition of an element can significantly improve the material quality, by reducing the number of defects. A specific category of these NWs is antimonides that promote a pure ZB crystal phase, due to the surfactant properties of Sb.…”

Doping Dependent Magnetic Behavior in MBE Grown GaAs1-xSbx Nanowires

“…Within the III-V materials, GaAsSb nanowires are particularly attractive due to their wide tunability of band gap within the 870-1700 nm (1.425-0.73 eV) regime of the electromagnetic spectrum and large carrier mobility (see ref. 10 and references therein). In addition, antimonide NW's have a relatively large exciton Bohr radius below which one anticipates quantum confinement compared to other III-V semiconductors.…”

“…In an axial configuration, these nanowires exhibit a pure zinc blende crystal structure with a reduced density of planar defects. The high structural and optical quality of GaAsSb axial nanowires has led to promising photodetectors 10,11 and subwavelength wire lasers 12 in the near-IR telecommunications wavelength range and high current density tunnel diodes 13 . Ganjipour, et al 14 fabricated a single hole transistor from a p-type GaSb nanowire and suggested that their results are relevant for spintronic applications and quantum information science since hole confinement in quantum systems can enhance the spin relaxation time.…”