GaAs nanodisks (NDs), with a thickness of 8 nm and a diameter of 15 nm, were directly fabricated from GaAs quantum wells (QW) by damage-free neutral-beam etching using bio-nanotemplates. We observed the electron g-factor and spin dephasing in NDs with different barrier heights in the lateral direction by means of time-resolved Kerr rotation. The magnitude of the g-factor depends on the degree of lateral confinement originating from enhanced penetration of the electron wavefunction from an ND into the surrounding AlGaAs barriers. The spin-dephasing time is also observed to be altered by ND formation. (C) 2015 Elsevier B.V. All rights reserved.