No abstract

The direct E,, E, + A , and indirect E r -x transition energies of Ini-,Ga,P crystals are studied by electromodulation and wavelength modulation methods a t 77 K and room temperature. TheE, energy at 77 K and room temperature obeys a parabolic relation as a function of composition x with a bowing parameter of b = 0.764 and 0.76 eV, respectively. The E r -x energy a t 77 K can be expressed by a linear x-dependence with slope 0.072 eV. The crossover point a t 77 K is determined as xc = 0.72 0.015; E , = (2.300 f 0.003) eV. The spin-orbit splitting A, shows an upward bowing with bowing parameter -0.060 eV.

Thermally induced strain caused by device packaging is studied in high-power semiconductor lasers by a noninvasive technique. Fourier-transform photocurrent measurements with intentionally strained laser array devices for 808 nm emission reveal spectral shifts of quantum-confined optical transitions in the optical active region. These shifts by up to 7 meV serve as a measure for strain and are compared with model calculations. For a given packaging architecture, about one quarter of the mounting-induced strain is transferred to the quantum-well region of the device. Spatially resolved measurements demonstrate a lateral strain gradient in the devices.

The advantages of the wavelength-modulation technique (1) a r e used here to in-Ga P mixed crystals and vestigate the weak structures in the indirect edge of In to observe the direct-indirect transition directly ~ because the corresponding x-value

We present the results on aging mechanisms acting in high-power laser diode arrays (LDAs) employing Fourier-transform (FT) spectroscopy. The FT spectrometer was used as an excitation source for performing photocurrent (PC) measurements in two sets of aged LDA samples. The PC spectra reveal both the evolution of a defect band located in the optically active layer as well as modifications of the interband part of the spectrum upon aging. Such changes represent sensitive quantitative measures of the aging status and provide insight into the microscopic changes of the device structure upon aging.