C. Shieh

Anomalous dependence of threshold current on stripe width in gain‐guided strained‐layer InGaAs/GaAs quantum well lasers

An anomalous dependence of the threshold current on the stripe width is observed for gain‐guided strained‐layer InGaAs/GaAs quantum well lasers. The threshold current increases strongly as the stripe width is reduced from relatively large values. This is attributed to the huge lateral loss caused by an unusually large index antiguide which manifests itself in the far‐field behavior. This large loss also leads to a population of higher quantized energy levels in the InGaAs quantum well strongly reducing the lasing wavelength by as much as 61 nm.

Study of impurity induced disordering in AlGaAsGaAs multi-quantum well structures by photothermal deflection spectroscopy and photoluminescence

Abstract Experiments for the investigation of selective disordering of AlGaAs GaAs multiple quantum well structures by zinc and sulfur diffusion were carried out. The absorption of the disordered structure was measured by the photothermal deflection spectroscopy. The zinc diffused structure showed a much larger residual absorption than the sulfur diffused structure. The sharpness of the lateral transition from the non-disordered structure to the disordered structure in the selective disordering by diffusion is better for sulfur diffusion than for zinc diffusion as revealed by TEM. Photoluminescence showed that the capping dielectric enhances the interdiffusion of AlGa at the high temperature necessary for sulfur diffusion. However, with proper capping conditions good selective disordering is achieved.

The Effect of Ar Sputtering on the Disordering of AlGaAs/GaAs Multiple Quantum Wells

The effect of Ar sputtering, in combination with different dielectric cappings, on the disordering of AlGaAs/GaAs multiple quantum wells was studied. It was found that the combination of Ar sputter etch and SiO 2 capping provided the strongest enhancement in disordering. This effect generates enough change in refractive index to produce an index guided laser.