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The nonlinear absorption coefficients of Si from 146 to 452°K and of CdSe, CdTe, and GaAs at 300°K were measured with a Nd:YAlG Q-switched laser. The reported stepwise nature of nonlinear absorption for Si is confirmed, but the assignment of a three-photon process is uncertain. As an optical limiter, the optimum Si thickness to be inserted within a Nd:laser cavity is discussed.

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Experimental studies have been performed on several aspects of the degradation of electroluminescent quantum efficiency in ZnO-doped GaP light-emitting diodes. The dependence of degradation on stress temperature, stress current (experienced during accelerated aging), and measurement current (at which quantum efficiency is evaluated) has been empirically determined from experiments on several lots of devices. It is shown that degradation is dominated by a decrease in bulk p-side radiative recombination efficiency. The degradation of other factors (such as injection efficiency and injection ratio) contributing to the overall electroluminescent efficiency has only a secondary effect. Moreover, it is shown empirically that the dependences of degradation on temperature and stress current are separable.

The light-current-voltage (LIV) characteristics of both red- and green-emitting GaP p-n junctions have been analyzed in detail at room temperature. Device current has been quantitively and accurately decomposed into components corresponding to the Sah-Noyce-Shockley space-charge recombination and to diffusion current. Data analysis is performed rapidly using an automatic iterative procedure developed for this purpose. In the course of calculation, diode resistance in series with the junction is measured and corrected for, thus considerably extending the upper limit of bias current which may be usefully studied. This study has also determined the current dependence of injection efficiency, electroluminescent quantum efficiency, and the effective luminescent recombination efficiency of the bulk semiconductor region adjacent to the junction. Although this method is applicable to broad classes of junction devices, its use involves certain limitations and ambiguities, which are explicitly discussed. This analysis has been applied to the LIV characteristics of representative examples of both red- and green-light-emitting GaP p-n junctions, grown by double liquid-phase epitaxy. For both these cases, it is demonstrated that the simple current models employed (SNS space charge and diffusion) are in excellent agreement with the observed I-V characteristics over more than nine decades of device current. It seems apparent that these techniques will prove relevant to studies of the physics of light-emitting diodes.