Suppression of defect propagation in semiconductors by pseudomorphic layers
The propagation of defects in semiconductor heterostructures has been studied both theoretically and experimentally. The simple model shows that defects originating from lattice‐matched regions can be prevented from entering, or can be trapped by, a pseudomorphic layer, depending on the signs of the strain induced by the defect and the strain in the pseudomorphic layer. A pseudomorphic layer can therefore prevent the defect from propagating across in and entering the critical active region of a device. Experimentally, the photoluminescence intensities of Al0.4Ga0.6As/GaAs quantum wells with and without pseudomorphic In0.2Ga0.8As layers for prevention of defect propagation have been compared. GaAs substrates of high etch pit density were used to generate defects below the quantum well and silicon implantation was used to generate defects above it. The elevated temperatures during molecular‐beam‐epitaxial growth and postimplant rapid thermal annealing serve to assist in defect propagation in the respective ...
Reliability of InAlGaAs strained-quantum-well lasers operating at 0.81 mu m
Preliminary reliability studies of strained In/sub 0.15/Al/sub 0.13/Ga/sub 0.72/As quantum-well lasers operating at 0.81 mu m are reported. InAlGaAs lasers, a possible replacement for AlGaAs lasers, have been studied with respect to three failure mechanisms. Uncoated In/sub 0.15/Al/sub 0.13/Ga/sub 0.72/As quantum-well lasers have exhibited catastrophic optical damage limits of 1.87 MW/cm/sup 2/, which is equal to that of similar AlGaAs lasers. Further, the lasers are both free of <100> DLD-induced sudden failures and exhibit low degradation rates even in this early stage of their development.<<ETX>>
AlInGaAs/AlGaAs strained quantum-well ridge waveguide lasers grown by metalorganic chemical vapor deposition
AlInGaAs/AlGaAs strained quantum-well ridge waveguide diode lasers with an emission wavelength of 890 nm are presented. These devices exhibit both single spatial and longitudinal mode operation up to 30 mW of optical output power. A CW threshold current of 13 mA was obtained for a 5- mu m-wide ridge waveguide having a cavity length of 500 mu m. The differential quantum efficiency was 52%. The lateral and perpendicular far-field radiation patterns (FWHM) from the laser were 6 degrees and 51 degrees , respectively. Reliability testing on uncoated gain-guided lasers made from the same wafer showed no sudden death failures and degradation rates as low as 4.6%/kh.<<ETX>>