How To Observe Charged Bosons in Quantum Wells?

We discuss the prospects of experimental observation of biholes in quantum wells of various popular cubic semiconductors. Biholes are charged exciton-like complexes formed by a couple of holes belonging to different subbands and having negative reduced effective mass. The biholes should be manifested as extra peaks in inter-subband absorption. The necessity of both high binding energy and long lifetime reveals competing requirements to the parameters of the quantum well; thus, the optimal design of the heterostructure becomes the key ingredient for the success.