Abstract
A detailed understanding of the optical properties of self-catalysed (SC), zinc blende (ZB) dominant, nanowires (NWs) is crucial for the development of functional and impurity-free nanodevices. Despite the fact that SC InAs NWs mostly crystallize in the WZ/ZB phase, there are very limited reports on the photoluminescence (PL) properties of ZB InAs NWs. Here, we report on the PL properties of Molecular Beam Epitaxy grown, SC InAs NWs. The as-grown NWs exhibit a dominant band to band (BtB) peak associated with ZB, InAs with an emission energy of ~0.41 eV in good agreement with the band gap energy of ZB InAs and significantly lower than that of the wurtzite phase (~0.48 eV). The strong BtB peak persists to near room temperature with a distinct temperature-dependent red-shift and very narrow spectral linewidth of ~20 meV (10 K) which is much smaller than previously reported values. A narrowing in PL linewidth with increasing NWs diameter is correlated with a decline in the influence of surface defects resulting from an enlargement in NWs diameter. This study demonstrates the high optical property of SC InAs NWs which is compatible with the Si-complementary metal-oxide-semiconductor technology and paves the way for the monolithic integration of InAs NWs with Si in novel nanodevices.
Highlights
A detailed understanding of the optical properties of self-catalysed (SC), zinc blende (ZB) dominant, nanowires (NWs) is crucial for the development of functional and impurity-free nanodevices
InAs NWs were grown on bare Si(111) substrates by molecular beam epitaxy (MBE) via an Indium droplet-assisted growth technique as described previously[19] under As-rich conditions (Beam equivalent pressure of ~10−6 and 10−7 mbar for As and In respectively) at a growth temperature of 440–500 °C for about 25 and 144 min for samples α and γ, respectively
The two samples clearly show a dominant band to band (BtB) emission at ~0.410 eV associated with ZB InAs22,24,29 which is consistent with the InAs epilayer (Fig. 1) and in good agreement with the bulk ZB-InAs band gap energy[30] but significantly lower than the WZ-InAs bandgap (~0.480 eV)[15] as well as the WZ-dominated (~0.455 eV)[31] and mixed WZ/ZB-phase InAs NWs16
Summary
A detailed understanding of the optical properties of self-catalysed (SC), zinc blende (ZB) dominant, nanowires (NWs) is crucial for the development of functional and impurity-free nanodevices. The two samples clearly show a dominant BtB emission (peak 3) at ~0.410 eV associated with ZB InAs22,24,29 which is consistent with the InAs epilayer (Fig. 1) and in good agreement with the bulk ZB-InAs band gap energy[30] but significantly lower than the WZ-InAs bandgap (~0.480 eV)[15] as well as the WZ-dominated (~0.455 eV)[31] and mixed WZ/ZB-phase InAs NWs16.
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