A developed Ullmann reaction to III–V semiconductor nanocrystals in sealed vacuum tubes

Abstract

Group III–V (13–15, III = Ga, In, and V = P, As) semiconductor nanocrystals were effectively obtained via a developed Ullmann reaction route through the reactions of preformed nanoscale metallic indium or commercial gallium with triphenylphosphine (PPh₃) and triphenylarsine (AsPh₃) in sealed vacuum quartz tubes under moderate conditions at 320–400 °C for 8–24 h. The developed synthetic strategy in sealed vacuum tubes extends the synthesis of III–V semiconductor materials, and the air-stable PPh₃ and AsPh₃ with low toxicity provide good alternative pnicogen precursors for the synthesis of III–V nanocrystals. The analysis of XRD, ED and HRTEM established the production of one-dimensional (1D) metastable wurtzite (W) InP, InAs and GaP nanostructures in the zinc blende (ZB) products. Further investigations showed that 1D W nanostructures resulted from kinetic effects under the moderate synthetic conditions employed and the steric effect of PPh₃ and AsPh₃, and that the tendency for the synthesis of III–V nanocrystals was in the orders of IIIP > IIIAs and GaV > InV on the basis of experiments and thermodynamic calculations. Meanwhile, the microstructures and growth mechanism of the III–V nanocrystals were investigated.