Within a p - n junction, the drift current is directed

In a $p$-$n$ junction, the depletion region contains uncovered positive donor ions on the $n$-side and negative acceptor ions on the $p$-side.

This charge distribution creates an internal electric field directed from the $n$-side towards the $p$-side.

The drift current is caused by the movement of minority charge carriers under the influence of this built-in electric field. Holes (minority carriers on the $n$-side) are swept towards the $p$-side, and electrons (minority carriers on the $p$-side) are swept towards the $n$-side.

The flow of positive charges from $n$ to $p$ and negative charges from $p$ to $n$ both contribute to a conventional current directed from the $n$-side to the $p$-side.

The direction of this drift current is independent of the external biasing.