Achievement

Michael Moewe and other trainees from the Chang-Hasnain lab have been working on a new growth mode in metal-organic chemical vapor deposition, generating III-V nanoneedles at low temperature (380-420 °C). The needles are catalyst-free, ultra-sharp GaAs structures, with record narrow tip diameters of less than 1 nm, sharp 6-9° taper angles, and lengths up to 10 µm. Crystals are pure wurtzite phase, exhibit bright room-temperature photoluminescence, and grow on GaAs and Si substrates. Also, InGaAs and AlGaAs core-shell heterostructure nanoneedles have been grown. Results of InGaAs quantum well nanoneedles having band edge emission tunable by 380 meV to below the silicon band edge were published, which can facilitate the use of optical devices utilizing silicon waveguides. Since these nanoneedles can be grown directly on silicon at silicon-transparent wavelengths, they have potential use for integration of optoelectronic materials with silicon CMOS integrated circuits.