In a PN Junction semiconductor, electrons combine with holes. Electrons in the N region are pretty mobile at room temperature which makes sense. However what is the force that attracts them towards "holes".
As far as I understand "holes" in a P-type semiconductor are because Boron (or any other impurity) has only 3 valence electrons and hence in the crystal formed there is always a possibility of one more electron to make it 8 valence electrons, octet formation. It is not because of an electron that has gone away due to some energy excitation and hence it is electrically neutral.
So what is the force (electromagnetic, gravitational, strong nuclear, weak nuclear) that causes a hole to capture an electron?