Image Number 3 for United States Patent #6359920.
Several methods are used in novel ways with newly identified and viable parameters to decrease the peak transition energies of the pseudomorphic InGaAs/GaAs heterostructures. These techniques, taken separately or in combination, suffice to permit operation of light emitting devices at wavelengths of 1.3 .mu.m or greater of light-emitting electro-optic devices. These methods or techniques, by example, include: (1) utilizing new superlattice structures having high In concentrations in the active region, (2) utilizing strain compensation to increase the usable layer thickness for quantum wells with appropriately high In concentrations, (3) utilizing appropriately small amounts of nitrogen (N) in the pseudomorphic InGaAsN/GaAs laser structure, and (4) use of nominal (111) oriented substrates to increase the usable layer thickness for quantum wells with appropriately high In concentrations. In all of the above techniques, gain offset may be utilized in VCSELs to detune the emission energy lower than the peak transition energy, by about 25 meV or even more, via appropriate DBR spacing. Gain offset may also be utilized in some forms of in-plane lasers. Increased temperature may also be used to decrease peak transition energy (and therefore the emission energy) by about 50 meV/100.degree. C. All these techniques are furthermore applicable to other material systems, for example, extending the emission wavelength for laser diodes grown on InP substrates. Additionally, structures which utilize the above techniques are discussed.
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