Synthesis of metallic, semiconducting, and semi-metallic nanowires through control of InSb growth parameters

Abstract

In this work we present a simple route to grow metallic, semiconducting or semi-metallic nanowires by chemical vapor deposition. Metallic indium (In), semiconducting indium antimonide (InSb) and semi-metallic antimony (Sb) nanowires were successfully synthesized by controlling temperature and hence Sb vapor pressure in the higher eutectic region of the InSb phase diagram. Semiconducting InSb nanowires were synthesized by direct antimonidization of In droplets at a temperature of 480 °C in an Sb-rich environment. I–V measurements on a single 50 nm thick InSb nanowire field-effect transistor show electrons to be the majority carriers with an electron concentration of ≈1018 cm−3. Thermally activated Arrhenius conduction was observed in the temperature range from 200–325 K, yielding an activation energy of 0.11 eV. Metallic In nanowires were grown at 600 °C, using a process similar to that for the growth of InSb nanowires. However, the higher growth temperature resulted in Sb re-evaporating from the growing nanowire crystal, leading to growth of In nanowires. The In nanowires were found to have an extremely high (≈1021 cm−3) electron concentration. Temperature dependent conductivity measurements show that at high temperatures the In nanowire conductivity varies as T−3/2, suggesting that acoustic phonons controlled electron transport. Antimony nanowire growth occurred at 400 °C by a self-catalyzed growth mechanism. Electron transport measurements on a single Sb nanowire reveal p-type conduction, with a hole concentration of ≈1019 cm−3. A higher hole mobility compared to electron mobility and the presence of surface states is the most likely cause of the hole-dominated conductivity in the Sb nanowires.