Improved Theory for Carrier Leakage and Diffusion in Multiquantum-well Semiconductor Lasers

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Abstract
A model of carrier leakage lifetime is presented taking into account the density of states for quantum-wells and band nonparabolicity. Rate equations are also proposed including leakage of both types of carriers and carrier loss in both sides of optical confinement layers. The carrier loss coefficients extracted by adopting this model on the measured modulation bandwidth of 1.5 µm-wavelength multiquantum-well lasers coincided with reported values within their distributions. Measured temperature sensitivity of threshold current and that of K factor were also well explained with the improved model using those extracted carrier loss coefficients. The dominant causes of low characteristic temperature T 0 of present compressive-strained multiquantum-well lasers were quantitatively considered and found to be attributed to 1) Auger carrier loss and 2) thermionic carrier leakage and diffusion delay effect. T 0 over 150 K is expected by reducing the effect of those two factors. Possibilities of finding an actual method to reduce the effect of the above two factors are discussed.