Spatially resolved photoluminescence line scans were performed to determine the local stresses in AlGaAs laser diodes designed for high-power operation at 808 nm. In this approach, the sign and magnitude of the local stress are deduced from the spectral shift of the peak associated with band-to-band transitions in the n-type GaAs substrate. The sensitivity of the technique (minimal equivalent hydrostatic stress that can be detected) can reach 10 MPa or better. Correlations between solder-induced stress distribution in the devices and estimated lifetimes are demonstrated.

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Spatially resolved photoluminescence (PL) measurements have been performed on GaAs/GaInAs/GaAlAs pseudomorphic high electron mobility transistors to determine the local temperature on both sides of the gate with spatial resolution of about 1 μm and temperature resolution better than 1 °C. This local temperature is deduced from the energy shift of one of the peaks in the PL spectra. Asymmetry in the temperature distribution between the drain and source sides is observed. The experimental temperature values have also been compared with predictions from an analytical model to determine the thermal resistance in these devices.

The technique of spatially resolved photoluminescence (PL) spectroscopy was used to determine the local channel temperatures on GaAs/GaInAs/GaAlAs pseudomorphic high electron mobility transistors. By focusing a laser beam onto the different regions of the DC-biased transistor, it is shown that the channel temperature can be determined from the energy shift of one of the peaks in the PL spectra, with a spatial resolution of about 1 pnm and a temperature resolution in the order of 1 'C. In particular, an asymmetry in the temperature distribution between the drain and source sides is observed. Using this approach, detailed temperature maps of the devices were obtained, as a function of the gate-source voltage VGS. These experimental temperature values are also compared with predictions derived from an analytical model of the thermal resistance in these devices.

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