Differential I/V of heterostructure correlates with laser threshold

Abstract
We report detailed measurements of current (I) vs voltage (V) on double heterojunctions (AlxGa1−xAs–GaAs–AlyGa1−yAs) at very high injection levels which reveal nearly discontinuous ∂2V/∂I2 at currents ∼ 30% below lasing threshold. This behavior persists unchanged after the laser mirrors are destroyed. A similar breakpoint in ∂2V/∂I2 is found on nonlasing double heterostructures and correlates with the onset of intense infrared emission.
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