High pressure measurements on visible spectrum AlxGa1−xAs heterostructure lasers: 7100–6750-Å 300-K operation

Pressure applied to high performance cw 300-K bulk-limit (Lz ~600 A) single quantum well heterostructure Alx Gal _ x As (x ~ 0.28, A ~ 7100 A) laser diodes is used to simulate composition change and determine the threshold increase at shorter wavelength. Unless small quantum well sizes are employed in more sophisticated designs it is unlikely that A (for cw 300-K operation) can be made much less than 6900 A

High pressure measurements on AlxGa1−xAs-GaAs (x = 0.5 and 1) superlattices and quantum well heterostructure lasers

Absorption data on AIAs-GaAs and Alx Gal _ x As-GaAs superlattices (SL's) and emission data on Alx Gal _ x As-GaAs quantum-well heterostructure (QWH) laser diodes subjected to hydrostatic pressure (0-10 kbar) at 300 K are presented. Superlattice absorption data show that the confined-particle transitions, which partition and "label" the r energy band high above the band edge, all move with the same pressure coefficient of 11.5 meV /kbar. (For bulk GaAs, the pressure coefficient is 12.5 me V /kbar. ) The effect of the L indirect minima on the highest observed confined-particle transitions is small; the effect of the X minima is large. At lower pressures, QWH diodes exhibit a pressure dependence similar to that of the free (unconstrained) SL's. The data on QWH diodes demonstrate, however, a size-dependent [Lz (GaAs) < 500 A] shift in slope to a lower (8.5 meV /kbar) energy gap versus pressure coefficient at higher pressures. This change in slope can be explained by considering the effect on the light- and heavy-hole subbands of shear stresses generated within the p-n diode heterostructure