| 摘要 |
The present invention relates to quantum well semiconductor light emitting devices such as lasers that utilize resonant tunneling for carrier injection and spatially-diagonal transitions between an energy state in the conduction band of one quantum well and an energy state in the valence band of the adjacent quantum well for light emission, resulting in much improvement in both radiative efficiency and carrier injection efficiency. An elementary structure of the invented devices comprises two spatially coupled quantum wells residing in conduction and valence bands respectively wherein the valence band-edge in one quantum well is higher than the conduction band-edge of the other quantum well. Each quantum well contains at least one energy state formed by the quantum size effect. Light emission occurs by the transition of electrons from the state which is higher in energy in the conduction band quantum well to the state in the valence band quantum well, and the emission wavelength is inversely proportional to the energy difference between the two states which can be easily tailored by adjusting quantum well thicknesses. Cascade emission is realized by periodically stacking many repeated elementary device structures.
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