We present a calculation of single-charge tunneling in a semiconductor quan
tum dot based on a full self-consistent tight-binding calculation of the ch
arging energies, applicable to quantum dots of realistic size (up to 8 nm d
iameter). Comparison with recent tunneling spectroscopy experiments on InAs
nanocrystals shows excellent agreement and allows an unambiguous assignati
on of the conductance peaks. For bias voltages V larger that the band gap o
f the quantum dot we show that both electrons and holes can tunnel into the
quantum dot, leading to specific features in the I(V) curves.