Quantifying the Effect of Indirect Carrier Leakage on Visible Al(GaInP) Lasers Using High Pressures and Low Temperatures

The extreme temperature sensitivity of the threshold current, Ith, above room temperature in visible edge-emitting lasers (EELs) is investigated. From measurements as a function of temperature we find that Ith is dominated by the radiative current, IRad up to ∼230 K so Ith ≈ IRad as expected for an ideal device. However, above 230 K, Ith increases sharply due to the onset of indirect carrier leakage which we calculate to be ∼20% of Ith at room temperature at an emission wavelength of 672 nm. By 350 K it accounts for >70% of Ith. The operating wavelength of the device can be reduced by applying pressure and then we observe that the leakage rapidly increases and at 655 nm it forms ∼70% of Ith at room temperature. This gives rise to a significant deterioration in the light output characteristics and has important implications for producing high power EELs and VCSEL structures based upon Al(GaInP) at these shorter operating wavelengths.