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The variation with temperature of laser threshold current density under pulsed operation conditions, Jt, has been measured for double heterostructure wafers grown with a range of values of heterojunction step height Δx. Good correlation is found between Δx and the temperature coefficient which is defined as the ratio of the values of Jt at 65 and 10 °C. Values of J65/J10 are found to be approximately 1.5 for Δx=0.30, increasing slowly to 2.0 at Δx=0.20 and increasing very rapidly for smaller values fo Δx. This behavior is interpreted as arising from leakage of electrons from the active region into the p passive layer. A theoretical model of carrier leakage confirms the interpretation in that quantitative agreement with experiment was obtained using reasonable values for the disposable parameters of carrier lifetime and mobility. The model is used to predict approximate limits to the Al concentrations in the passive layers needed for stable continuous laser operation over a wide temperature range.

The temperature dependence of degradation mechanisms in longlived (GaAl)As DH lasers

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