Some Design Considerations for Multi-Quantum-Well Lasers

This paper addresses itself to two different problems in the design of multi-quantum-well (MQW) lasers: (a) The problem of inter-well coupling by electron tunneling is investigated, and it is shown that the tunneling can be made sufficiently strong to permit efficient electron equilibration between wells, without destroying the advantages of the step-like distribution of states of a single well or of fully decoupled wells. (b) A modification of the quantum well array itself is proposed, in which additional narrower quantum wells are added outside the lasing well array itself. These subsidiary welts contain only a negligible concentration of electrons and hence do not participate in the laser action, but they should improve the quality of the epitaxial growth, and assist in both the electron capture and the optical confinement.