In quantum mechanics the time-independent Schrodinger's equation can be solved for eigenfunctions (also called eigenstates or wave-functions) and corresponding eigenenergies (or energy levels) for a stationary physical system. The wavefunction itself can take on negative and positive values and could be complex.
The square magnitude of the wave-function is the probability density of finding the particle in space at that particular energy level.
A quantum dot is a physical system that can confine electrons or holes in all three spatial dimensions. The image above shows how stationary wave functions look in box and pyramid-shaped quantum dots. Energy states in rectangular dots are more s-type and p-type in character (i.e., they maintain orbital symmetry). However, in a pyramid-shaped dot the wave functions are mixed due to the asymmetry of the confinement.